[PATCH v3] ALSA: hda/ca0132: Add Sound BlasterX AE-5 external RGB LED strip support

[PATCH v3] ALSA: hda/ca0132: Add Sound BlasterX AE-5 external RGB LED strip support

[Devin Christensen]

The Sound BlasterX AE-5 and AE-5 Plus expose a 3-pin 5V addressable RGB
header driven directly by the CA0113 PCIe-to-HD-Audio bridge. Rather
than using the CA0132 DSP or MMIO GPIO, the CA0113 contains an
autonomous HDA link sniffer that snoops a designated HDA DMA playback
stream, extracts the 24-bit GRB color payload, and serializes it as
800 kHz single-wire NRZ pulses to the strip (WS2812B protocol).

Expose the strip through volatile card control elements:

  "AE-5 LED Strip"        (RW, BYTES): 300-byte RGB payload representing
                          up to 100 addressable LEDs (3 bytes per LED).
  "AE-5 LED Strip Count"  (RW, INTEGER): Active LED count (1..100).

The controls are marked with IFACE_CARD and SNDRV_CTL_ELEM_ACCESS_VOLATILE
so changes do not trigger unnecessary audio daemon wakeups or state
restoration by alsactl.

Writes allocate an idle HDA playback stream, format a 32 KB DMA buffer
populated with repeating WS2812 frames (preamble, audio words per LED,
and reset gap), configure the CA0113 BAR2 serializers and stream-tag
pin mux, and pulse the stream long enough for the reset latch to fire.
Access is serialized with a per-spec mutex, and the controls are only
registered on QUIRK_AE5 devices.

The strip transport uses snd_hdac_dsp_prepare() / snd_hdac_dsp_cleanup(),
which require CONFIG_SND_HDA_DSP_LOADER. All strip-related code and struct
fields are conditionally compiled under
IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER), with a no-op stub for
ae5_add_strip_controls() when disabled.

Signed-off-by: Devin Christensen <dchristensen8@proton.me>
---
v3:
 - Move #include <linux/dma-mapping.h> into main header block.
 - Check s->opened in ae5_strip_find_stream() to avoid stealing open streams.
 - Guard all strip code and struct members with IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
   and provide a static inline stub for ae5_add_strip_controls().
 - Return 1 from put callbacks when values change (using memcmp on colors).

v2:
 - Use CLASS(snd_hda_power_pm, pm)(codec) for RAII power management.
 - Switch userspace interface from sysfs to volatile card control elements
   ("AE-5 LED Strip" and "AE-5 LED Strip Count").

 sound/hda/codecs/ca0132.c | 387 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 386 insertions(+), 1 deletion(-)

diff --git a/sound/hda/codecs/ca0132.c b/sound/hda/codecs/ca0132.c
index 0f8fb62f0..036ae7358 100644
--- a/sound/hda/codecs/ca0132.c
+++ b/sound/hda/codecs/ca0132.c
@@ -18,6 +18,7 @@
 #include <linux/types.h>
 #include <linux/io.h>
 #include <linux/pci.h>
+#include <linux/dma-mapping.h>
 #include <asm/io.h>
 #include <sound/core.h>
 #include <sound/hda_codec.h>
@@ -1060,6 +1061,8 @@ enum dsp_download_state {
  * CA0132 specific
  */
 
+#define AE5_STRIP_MAX_LEDS 100
+
 struct ca0132_spec {
 	struct hda_gen_spec gen;
 
@@ -1162,6 +1165,13 @@ struct ca0132_spec {
 	 * Renames PlayEnhancement and CrystalVoice too.
 	 */
 	bool use_alt_controls;
+
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	/* AE-5 WS2812 strip control */
+	struct mutex ae5_strip_mutex;
+	u32 ae5_strip_cur_colors[AE5_STRIP_MAX_LEDS];
+	int ae5_strip_cur_num_leds;
+#endif
 };
 
 /*
@@ -6846,6 +6856,15 @@ static int ca0132_alt_add_mic_boost_enum(struct hda_codec *codec)
 
 }
 
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+static int ae5_add_strip_controls(struct hda_codec *codec);
+#else
+static inline int ae5_add_strip_controls(struct hda_codec *codec)
+{
+	return 0;
+}
+#endif
+
 /*
  * Add headphone gain enumerated control for the AE-5. This switches between
  * three modes, low, medium, and high. When non-headphone outputs are selected,
@@ -7149,6 +7168,10 @@ static int ca0132_build_controls(struct hda_codec *codec)
 
 	switch (ca0132_quirk(spec)) {
 	case QUIRK_AE5:
+		err = ae5_add_strip_controls(codec);
+		if (err < 0)
+			return err;
+		fallthrough;
 	case QUIRK_AE7:
 		err = ae5_add_headphone_gain_enum(codec);
 		if (err < 0)
@@ -8316,8 +8339,363 @@ static void sbz_setup_defaults(struct hda_codec *codec)
 }
 
 /*
- * Setup default parameters for the Sound BlasterX AE-5 DSP.
+ * Sound BlasterX AE-5 External WS2812B RGB LED Strip Transport
  */
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+#define AE5_STRIP_DMA_SIZE		0x8000
+#define AE5_STRIP_TOTAL_WORDS		(AE5_STRIP_DMA_SIZE / sizeof(u32))
+#define AE5_STRIP_PREAMBLE_WORDS	5
+#define AE5_STRIP_WORDS_PER_LED		4
+#define AE5_STRIP_RESET_GAP_WORDS	83
+
+#define CA0113_SERIALIZER_BASE(spec, ch)	((spec)->mem_base + 0x42c + (ch) * 0x40)
+#define CA0113_SERIALIZER_CLK(spec, ch)		((spec)->mem_base + 0x43c + (ch) * 0x40)
+#define CA0113_SERIALIZER_OUT(spec, ch)		((spec)->mem_base + 0x454 + (ch) * 0x40)
+
+static void ae5_strip_encode_24(u32 u, u32 *words)
+{
+	/*
+	 * 24-bit pixel -> 4 x 32-bit audio words (6 bits per word).
+	 * Hardware audio serializer transmits MSB first (bits 31 down to 0).
+	 * For word i (i8 = 23, 17, 11, 5), bit_idx 0..5 (MSB to LSB within the word)
+	 * is placed at n = 29 - bit_idx * 4:
+	 *   Bit 0 -> 0b100 << n (375ns high, 1042ns low): BIT(n + 2)
+	 *   Bit 1 -> 0b111 << n (1083ns high, 333ns low): BIT(n + 2) | BIT(n + 1) | BIT(n)
+	 */
+	int i8 = 23;
+	int i, bit_idx;
+
+	for (i = 0; i < 4; i++) {
+		u32 out = 0;
+
+		for (bit_idx = 0; bit_idx < 6; bit_idx++) {
+			int bit = (u >> (i8 - bit_idx)) & 1;
+			int n = 29 - bit_idx * 4;
+
+			out |= (bit ? (BIT(2) | BIT(1) | BIT(0)) : BIT(2)) << n;
+		}
+		words[i] = out;
+		i8 -= 6;
+	}
+}
+
+static struct hdac_stream *ae5_strip_find_stream(struct hda_codec *codec)
+{
+	struct ca0132_spec *spec = codec->spec;
+	struct hdac_bus *bus = &codec->bus->core;
+	struct hdac_stream *s, *dsp = NULL, *first = NULL;
+
+	guard(spinlock_irqsave)(&bus->reg_lock);
+	list_for_each_entry(s, &bus->stream_list, list) {
+		if (s->direction != SNDRV_PCM_STREAM_PLAYBACK)
+			continue;
+		if (s->opened || s->running || s->locked)
+			continue;
+		if (!first)
+			first = s;
+		/* The DSP DMA consumes the DSP-loader stream (tag in dsp_stream_id). */
+		if (spec->dsp_stream_id && s->stream_tag == spec->dsp_stream_id)
+			dsp = s;
+	}
+
+	return dsp ? dsp : first;
+}
+
+/*
+ * Caller must hold spec->ae5_strip_mutex.
+ */
+static int ae5_strip_send_frame(struct hda_codec *codec, const u32 *grb_colors, int num_leds)
+{
+	struct ca0132_spec *spec = codec->spec;
+	struct snd_dma_buffer dmab;
+	struct hdac_stream *hstr = NULL;
+	unsigned int format, stream_tag;
+	u32 enc_words[4];
+	u32 *dst;
+	int word_idx = 0;
+	int frame_words;
+	int led, w, i;
+	int retries = 20; /* ~100ms max */
+	u8 orig_sd_ctl = 0;
+
+	if (!spec || !spec->mem_base)
+		return -ENODEV;
+	if (num_leds <= 0 || num_leds > AE5_STRIP_MAX_LEDS)
+		return -EINVAL;
+
+	lockdep_assert_held(&spec->ae5_strip_mutex);
+
+	CLASS(snd_hda_power_pm, pm)(codec);
+
+	/*
+	 * 44.1kHz, 24-bit, 2-channel format (0x4031) matches Windows CtxHda
+	 * HDAUDIO_STREAM_FORMAT.
+	 */
+	format = snd_hdac_stream_format(2, 24, 44100);
+
+	for (;;) {
+		hstr = ae5_strip_find_stream(codec);
+		if (!hstr) {
+			if (--retries <= 0) {
+				codec_warn(codec, "AE5 strip: no free azx stream after retries\n");
+				return -EBUSY;
+			}
+			usleep_range(5000, 10000);
+			continue;
+		}
+
+		stream_tag = snd_hdac_dsp_prepare(hstr, format, AE5_STRIP_DMA_SIZE, &dmab);
+		if ((int)stream_tag > 0)
+			break;
+
+		/* Prepare failed (e.g. -EBUSY due to race with playback starting); retry */
+		if (--retries <= 0) {
+			codec_warn(codec, "AE5 strip: snd_hdac_dsp_prepare failed %d\n",
+				   (int)stream_tag);
+			return (int)stream_tag;
+		}
+		usleep_range(5000, 10000);
+	}
+
+	/* Prevent interrupt storms during free-running LED stream, saving original control bits */
+	if (hstr->sd_addr) {
+		orig_sd_ctl = readb(hstr->sd_addr);
+		writeb(orig_sd_ctl & ~0x1c, hstr->sd_addr); /* Clear IOCE, FEIE, DEIE */
+	}
+
+	/* 1. Populate the 32KB DMA buffer with repeating WS2812 frames + reset gaps */
+	memset(dmab.area, 0, AE5_STRIP_DMA_SIZE);
+	dst = (u32 *)dmab.area;
+
+	/* Words per frame: preamble + (num_leds * words_per_led) + reset gap */
+	frame_words = AE5_STRIP_PREAMBLE_WORDS + (num_leds * AE5_STRIP_WORDS_PER_LED) +
+		      AE5_STRIP_RESET_GAP_WORDS;
+
+	while (word_idx + frame_words <= AE5_STRIP_TOTAL_WORDS) {
+		/* Preamble per Windows CtxHda FUN_00042944 */
+		for (w = 0; w < AE5_STRIP_PREAMBLE_WORDS; w++) {
+			*dst++ = 0;
+			word_idx++;
+		}
+		/* LEDs */
+		for (led = 0; led < num_leds; led++) {
+			ae5_strip_encode_24(grb_colors[led], enc_words);
+			for (w = 0; w < AE5_STRIP_WORDS_PER_LED; w++) {
+				*dst++ = enc_words[w];
+				word_idx++;
+			}
+		}
+		/* Zero reset gap (> 1.8 ms; WS2812 requires > 50 us low) */
+		for (w = 0; w < AE5_STRIP_RESET_GAP_WORDS; w++) {
+			*dst++ = 0;
+			word_idx++;
+		}
+	}
+	while (word_idx < AE5_STRIP_TOTAL_WORDS) {
+		*dst++ = 0;
+		word_idx++;
+	}
+	/* Ensure DMA buffer writes are committed before triggering the HDA stream */
+	wmb();
+
+	/* 2. Configure CA0113 BAR2 hardware registers */
+	/* Power up clocks (CtxHdb 0x141b7 / 0x14210) */
+	writel(readl(spec->mem_base + 0xc04) | 0x7, spec->mem_base + 0xc04);
+
+	/* Base serializer initialization (CtxHdb 0x14ba4) */
+	writel(readl(spec->mem_base + 0x400) | 1, spec->mem_base + 0x400);
+	for (i = 0; i < 4; i++) {
+		writel(readl(CA0113_SERIALIZER_BASE(spec, i)) & ~1,
+		       CA0113_SERIALIZER_BASE(spec, i));
+		writel(0, CA0113_SERIALIZER_CLK(spec, i));
+	}
+	writel(readl(spec->mem_base + 0x408) | 1, spec->mem_base + 0x408);
+	writel(readl(spec->mem_base + 0x40c) | 1, spec->mem_base + 0x40c);
+	writel((readl(spec->mem_base + 0x410) & ~0xb) | 0x14, spec->mem_base + 0x410);
+
+	/* Configure serializers 0..3 clocking (CtxHdb 0x14a6c) */
+	for (i = 0; i < 4; i++)
+		writel(readl(CA0113_SERIALIZER_CLK(spec, i)) | 0x33,
+		       CA0113_SERIALIZER_CLK(spec, i));
+
+	/* BAR2 + 0x100 format & channel enables:
+	 * - base 0x70f
+	 * - bit 28 = 1 (24-bit audio format via CtxHdb 0x14f58)
+	 * - bits 29..31 = 1 (44.1 kHz sample rate via CtxHdb 0x14fa4)
+	 * - bits 4..7 = 0xf (stage 1 enables)
+	 * - bits 12..15 = 0xf (stage 2 enables)
+	 * => 0x3000ff8f
+	 */
+	writel((readl(spec->mem_base + 0x100) & ~0xe000ffff) | 0x3000ff8f, spec->mem_base + 0x100);
+
+	/* Enable serializer output drivers for pins 0..3 (CtxHdb 0x14e94) */
+	for (i = 0; i < 4; i++)
+		writel(readl(CA0113_SERIALIZER_OUT(spec, i)) | 1,
+		       CA0113_SERIALIZER_OUT(spec, i));
+
+	/* Route all channels 0..3 to stream_tag (CtxHdb 0x1502c) */
+	writel((stream_tag << 28) | (stream_tag << 20) | (stream_tag << 12) | (stream_tag << 4),
+	       spec->mem_base + 0x104);
+
+	/* Enable CA0113 MMIO GPIO 0 & 1 */
+	ca0113_mmio_gpio_set(codec, 0, true);
+	ca0113_mmio_gpio_set(codec, 1, true);
+
+	codec_dbg(codec, "AE5 strip: send_frame: num_leds=%d stream_tag=%u (0x%08x)\n",
+		  num_leds, stream_tag, readl(spec->mem_base + 0x104));
+
+	/* 3. Trigger stream transmission on HDA link */
+	snd_hdac_dsp_trigger(hstr, true);
+	/*
+	 * WS2812 latches on the >50us reset gap after one frame. The 32KB buffer holds ~64
+	 * repeating frame+reset cycles; at ~1.4ms/frame a 15ms run transmits ~10 complete
+	 * cycles - more than enough to latch reliably. Keep it short so rapid sysfs writes
+	 * (OpenRGB effects/theme changes) are not serialized behind a 1s blocking sleep.
+	 */
+	usleep_range(15000, 20000);
+	snd_hdac_dsp_trigger(hstr, false);
+	codec_dbg(codec, "AE5 strip: trigger complete\n");
+
+	/* Teardown: clear 0x104 pin mux back to 0 */
+	writel(0x00000000, spec->mem_base + 0x104);
+
+	/* Restore descriptor control register */
+	if (hstr->sd_addr)
+		writeb(orig_sd_ctl, hstr->sd_addr);
+
+	snd_hdac_dsp_cleanup(hstr, &dmab);
+	return 0;
+}
+
+static int ae5_strip_ctl_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
+	uinfo->count = AE5_STRIP_MAX_LEDS * 3;
+	return 0;
+}
+
+static int ae5_strip_ctl_get(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	int i;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	for (i = 0; i < spec->ae5_strip_cur_num_leds; i++) {
+		u32 grb = spec->ae5_strip_cur_colors[i];
+
+		ucontrol->value.bytes.data[i * 3 + 0] = (grb >> 8) & 0xff;
+		ucontrol->value.bytes.data[i * 3 + 1] = (grb >> 16) & 0xff;
+		ucontrol->value.bytes.data[i * 3 + 2] = grb & 0xff;
+	}
+	if (spec->ae5_strip_cur_num_leds < AE5_STRIP_MAX_LEDS)
+		memset(&ucontrol->value.bytes.data[spec->ae5_strip_cur_num_leds * 3], 0,
+		       (AE5_STRIP_MAX_LEDS - spec->ae5_strip_cur_num_leds) * 3);
+	return 0;
+}
+
+static int ae5_strip_ctl_put(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	u32 colors[AE5_STRIP_MAX_LEDS];
+	int i, num_leds, change;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	num_leds = spec->ae5_strip_cur_num_leds;
+	for (i = 0; i < num_leds; i++) {
+		u8 r = ucontrol->value.bytes.data[i * 3 + 0];
+		u8 g = ucontrol->value.bytes.data[i * 3 + 1];
+		u8 b = ucontrol->value.bytes.data[i * 3 + 2];
+
+		colors[i] = ((u32)g << 16) | ((u32)r << 8) | (u32)b;
+	}
+	change = memcmp(spec->ae5_strip_cur_colors, colors,
+			sizeof(u32) * num_leds) != 0;
+	if (change)
+		memcpy(spec->ae5_strip_cur_colors, colors,
+		       sizeof(u32) * num_leds);
+	ae5_strip_send_frame(codec, colors, num_leds);
+	return change;
+}
+
+static int ae5_strip_num_leds_info(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = 1;
+	uinfo->value.integer.max = AE5_STRIP_MAX_LEDS;
+	return 0;
+}
+
+static int ae5_strip_num_leds_get(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	ucontrol->value.integer.value[0] = spec->ae5_strip_cur_num_leds;
+	return 0;
+}
+
+static int ae5_strip_num_leds_put(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	int val = ucontrol->value.integer.value[0];
+
+	if (val < 1 || val > AE5_STRIP_MAX_LEDS)
+		return -EINVAL;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	if (spec->ae5_strip_cur_num_leds == val)
+		return 0;
+	spec->ae5_strip_cur_num_leds = val;
+	ae5_strip_send_frame(codec, spec->ae5_strip_cur_colors, val);
+	return 1;
+}
+
+static const struct snd_kcontrol_new ae5_strip_ctls[] = {
+	{
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.name = "AE-5 LED Strip",
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info = ae5_strip_ctl_info,
+		.get = ae5_strip_ctl_get,
+		.put = ae5_strip_ctl_put,
+	},
+	{
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.name = "AE-5 LED Strip Count",
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info = ae5_strip_num_leds_info,
+		.get = ae5_strip_num_leds_get,
+		.put = ae5_strip_num_leds_put,
+	},
+};
+
+static int ae5_add_strip_controls(struct hda_codec *codec)
+{
+	int i, err;
+
+	for (i = 0; i < ARRAY_SIZE(ae5_strip_ctls); i++) {
+		err = snd_hda_ctl_add(codec, 0,
+				      snd_ctl_new1(&ae5_strip_ctls[i], codec));
+		if (err < 0)
+			return err;
+	}
+	return 0;
+}
+#endif /* CONFIG_SND_HDA_DSP_LOADER */
+
 static void ae5_setup_defaults(struct hda_codec *codec)
 {
 	struct ca0132_spec *spec = codec->spec;
@@ -8741,6 +9119,10 @@ static void ca0132_init_chip(struct hda_codec *codec)
 	unsigned int on;
 
 	mutex_init(&spec->chipio_mutex);
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	mutex_init(&spec->ae5_strip_mutex);
+	spec->ae5_strip_cur_num_leds = 10;
+#endif
 
 	/*
 	 * The Windows driver always does this upon startup, which seems to
@@ -9626,6 +10008,9 @@ static void ca0132_free(struct hda_codec *codec)
 #ifdef CONFIG_PCI
 	if (spec->mem_base)
 		pci_iounmap(codec->bus->pci, spec->mem_base);
+#endif
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	mutex_destroy(&spec->ae5_strip_mutex);
 #endif
 	kfree(spec->spec_init_verbs);
 	kfree(codec->spec);
-- 
2.55.0

Re: [PATCH v3] ALSA: hda/ca0132: Add Sound BlasterX AE-5 external RGB LED strip support

[Takashi Iwai]

On Mon, 05 Oct 2026 16:13:12 +0200,
Devin Christensen wrote:
> 
> The Sound BlasterX AE-5 and AE-5 Plus expose a 3-pin 5V addressable RGB
> header driven directly by the CA0113 PCIe-to-HD-Audio bridge. Rather
> than using the CA0132 DSP or MMIO GPIO, the CA0113 contains an
> autonomous HDA link sniffer that snoops a designated HDA DMA playback
> stream, extracts the 24-bit GRB color payload, and serializes it as
> 800 kHz single-wire NRZ pulses to the strip (WS2812B protocol).
> 
> Expose the strip through volatile card control elements:
> 
>   "AE-5 LED Strip"        (RW, BYTES): 300-byte RGB payload representing
>                           up to 100 addressable LEDs (3 bytes per LED).
>   "AE-5 LED Strip Count"  (RW, INTEGER): Active LED count (1..100).
> 
> The controls are marked with IFACE_CARD and SNDRV_CTL_ELEM_ACCESS_VOLATILE
> so changes do not trigger unnecessary audio daemon wakeups or state
> restoration by alsactl.
> 
> Writes allocate an idle HDA playback stream, format a 32 KB DMA buffer
> populated with repeating WS2812 frames (preamble, audio words per LED,
> and reset gap), configure the CA0113 BAR2 serializers and stream-tag
> pin mux, and pulse the stream long enough for the reset latch to fire.
> Access is serialized with a per-spec mutex, and the controls are only
> registered on QUIRK_AE5 devices.
> 
> The strip transport uses snd_hdac_dsp_prepare() / snd_hdac_dsp_cleanup(),
> which require CONFIG_SND_HDA_DSP_LOADER. All strip-related code and struct
> fields are conditionally compiled under
> IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER), with a no-op stub for
> ae5_add_strip_controls() when disabled.
> 
> Signed-off-by: Devin Christensen <dchristensen8@proton.me>

Now you got a few interesting points spotted by Sashiko review.
  https://sashiko.dev/#/patchset/20261005141244.2130023-1-dchristensen8%40proton.me

Could you take a look?


thanks,

Takashi

[PATCH v4] ALSA: hda/ca0132: Add Sound BlasterX AE-5 external RGB LED strip support

[Devin Christensen]

The Sound BlasterX AE-5 and AE-5 Plus expose a 3-pin 5V addressable RGB
header driven directly by the CA0113 PCIe-to-HD-Audio bridge. Rather
than using the CA0132 DSP or MMIO GPIO, the CA0113 contains an
autonomous HDA link sniffer that snoops a designated HDA DMA playback
stream, extracts the 24-bit GRB color payload, and serializes it as
800 kHz single-wire NRZ pulses to the strip (WS2812B protocol).

Expose the strip through volatile card control elements:

  "AE-5 LED Strip"        (RW, BYTES): 300-byte RGB payload representing
                          up to 100 addressable LEDs (3 bytes per LED).
  "AE-5 LED Strip Count"  (RW, INTEGER): Active LED count (1..100).

The controls are marked with IFACE_CARD and SNDRV_CTL_ELEM_ACCESS_VOLATILE
so changes do not trigger unnecessary audio daemon wakeups or state
restoration by alsactl.

Writes allocate an idle HDA playback stream, format a 32 KB DMA buffer
populated with repeating WS2812 frames (preamble, audio words per LED,
and reset gap), configure the CA0113 BAR2 serializers and stream-tag
pin mux, and pulse the stream long enough for the reset latch to fire.
Access is serialized with a per-spec mutex, and the controls are only
registered on QUIRK_AE5 devices.

The strip transport uses snd_hdac_dsp_prepare() / snd_hdac_dsp_cleanup(),
which require CONFIG_SND_HDA_DSP_LOADER. All strip-related code and struct
fields are conditionally compiled under
IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER), with a no-op stub for
ae5_add_strip_controls() when disabled.

Signed-off-by: Devin Christensen <dchristensen8@proton.me>
---
Went through the Sashiko report. Several were solid catches and are fixed
in v4:

- Fixed the TOCTOU race in ae5_strip_find_stream(): marked s->opened = 1
  under bus->reg_lock (and cleared on cleanup) so concurrent PCM playback
  can't steal the stream out from under it.
- Added a check for pm.err right after CLASS(snd_hda_power_pm, pm) to bail
  out cleanly if powering up fails.
- Propagated errors in the put callbacks instead of ignoring
  ae5_strip_send_frame() failures, so userspace actually gets the error and
  we don't commit unapplied state.
- Used cpu_to_le32() when filling DMA buffer words for big-endian safety.
- Dropped the manual SD_CTL interrupt mask clearing — like Sashiko pointed
  out, snd_hdac_stream_start() overwrote it anyway, and no_period_wakeup
  already prevents period interrupts.

The other two points were false positives (ca0132_init_chip() only runs on
probe, not resume; and the MMIO RMW collision cited code that doesn't exist
in ca0113_mmio_command_set()).

Thanks,
Devin

v4:
 - Reserve HDA stream by marking s->opened = 1 under bus->reg_lock in
   ae5_strip_find_stream(), and clear on completion/error, preventing
   TOCTOU race with concurrent PCM stream assignment.
 - Check pm.err after CLASS(snd_hda_power_pm, pm)(codec) to avoid MMIO/DMA
   access on suspended or failed-to-resume devices.
 - Check return value of ae5_strip_send_frame() in control put callbacks,
   propagating errors to userspace and avoiding uncommitted state divergence.
 - Write DMA buffer words using cpu_to_le32() for big-endian architecture
   safety.
 - Remove redundant/overwritten orig_sd_ctl save and interrupt mask clearing.

v3:
 - Move #include <linux/dma-mapping.h> into main header block.
 - Check s->opened in ae5_strip_find_stream() to avoid stealing open streams.
 - Guard all strip code and struct members with IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
   and provide a static inline stub for ae5_add_strip_controls().
 - Return 1 from put callbacks when values change (using memcmp on colors).

v2:
 - Use CLASS(snd_hda_power_pm, pm)(codec) for RAII power management.
 - Switch userspace interface from sysfs to volatile card control elements
   ("AE-5 LED Strip" and "AE-5 LED Strip Count").

 sound/hda/codecs/ca0132.c | 394 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 393 insertions(+), 1 deletion(-)

diff --git a/sound/hda/codecs/ca0132.c b/sound/hda/codecs/ca0132.c
index 0f8fb62f0..47aadd6f9 100644
--- a/sound/hda/codecs/ca0132.c
+++ b/sound/hda/codecs/ca0132.c
@@ -18,6 +18,7 @@
 #include <linux/types.h>
 #include <linux/io.h>
 #include <linux/pci.h>
+#include <linux/dma-mapping.h>
 #include <asm/io.h>
 #include <sound/core.h>
 #include <sound/hda_codec.h>
@@ -1060,6 +1061,8 @@ enum dsp_download_state {
  * CA0132 specific
  */
 
+#define AE5_STRIP_MAX_LEDS 100
+
 struct ca0132_spec {
 	struct hda_gen_spec gen;
 
@@ -1162,6 +1165,13 @@ struct ca0132_spec {
 	 * Renames PlayEnhancement and CrystalVoice too.
 	 */
 	bool use_alt_controls;
+
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	/* AE-5 WS2812 strip control */
+	struct mutex ae5_strip_mutex;
+	u32 ae5_strip_cur_colors[AE5_STRIP_MAX_LEDS];
+	int ae5_strip_cur_num_leds;
+#endif
 };
 
 /*
@@ -6846,6 +6856,15 @@ static int ca0132_alt_add_mic_boost_enum(struct hda_codec *codec)
 
 }
 
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+static int ae5_add_strip_controls(struct hda_codec *codec);
+#else
+static inline int ae5_add_strip_controls(struct hda_codec *codec)
+{
+	return 0;
+}
+#endif
+
 /*
  * Add headphone gain enumerated control for the AE-5. This switches between
  * three modes, low, medium, and high. When non-headphone outputs are selected,
@@ -7149,6 +7168,10 @@ static int ca0132_build_controls(struct hda_codec *codec)
 
 	switch (ca0132_quirk(spec)) {
 	case QUIRK_AE5:
+		err = ae5_add_strip_controls(codec);
+		if (err < 0)
+			return err;
+		fallthrough;
 	case QUIRK_AE7:
 		err = ae5_add_headphone_gain_enum(codec);
 		if (err < 0)
@@ -8316,8 +8339,370 @@ static void sbz_setup_defaults(struct hda_codec *codec)
 }
 
 /*
- * Setup default parameters for the Sound BlasterX AE-5 DSP.
+ * Sound BlasterX AE-5 External WS2812B RGB LED Strip Transport
  */
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+#define AE5_STRIP_DMA_SIZE		0x8000
+#define AE5_STRIP_TOTAL_WORDS		(AE5_STRIP_DMA_SIZE / sizeof(u32))
+#define AE5_STRIP_PREAMBLE_WORDS	5
+#define AE5_STRIP_WORDS_PER_LED		4
+#define AE5_STRIP_RESET_GAP_WORDS	83
+
+#define CA0113_SERIALIZER_BASE(spec, ch)	((spec)->mem_base + 0x42c + (ch) * 0x40)
+#define CA0113_SERIALIZER_CLK(spec, ch)		((spec)->mem_base + 0x43c + (ch) * 0x40)
+#define CA0113_SERIALIZER_OUT(spec, ch)		((spec)->mem_base + 0x454 + (ch) * 0x40)
+
+static void ae5_strip_encode_24(u32 u, u32 *words)
+{
+	/*
+	 * 24-bit pixel -> 4 x 32-bit audio words (6 bits per word).
+	 * Hardware audio serializer transmits MSB first (bits 31 down to 0).
+	 * For word i (i8 = 23, 17, 11, 5), bit_idx 0..5 (MSB to LSB within the word)
+	 * is placed at n = 29 - bit_idx * 4:
+	 *   Bit 0 -> 0b100 << n (375ns high, 1042ns low): BIT(n + 2)
+	 *   Bit 1 -> 0b111 << n (1083ns high, 333ns low): BIT(n + 2) | BIT(n + 1) | BIT(n)
+	 */
+	int i8 = 23;
+	int i, bit_idx;
+
+	for (i = 0; i < 4; i++) {
+		u32 out = 0;
+
+		for (bit_idx = 0; bit_idx < 6; bit_idx++) {
+			int bit = (u >> (i8 - bit_idx)) & 1;
+			int n = 29 - bit_idx * 4;
+
+			out |= (bit ? (BIT(2) | BIT(1) | BIT(0)) : BIT(2)) << n;
+		}
+		words[i] = out;
+		i8 -= 6;
+	}
+}
+
+static struct hdac_stream *ae5_strip_find_stream(struct hda_codec *codec)
+{
+	struct ca0132_spec *spec = codec->spec;
+	struct hdac_bus *bus = &codec->bus->core;
+	struct hdac_stream *s, *dsp = NULL, *first = NULL;
+
+	guard(spinlock_irqsave)(&bus->reg_lock);
+	list_for_each_entry(s, &bus->stream_list, list) {
+		if (s->direction != SNDRV_PCM_STREAM_PLAYBACK)
+			continue;
+		if (s->opened || s->running || s->locked)
+			continue;
+		if (!first)
+			first = s;
+		/* The DSP DMA consumes the DSP-loader stream (tag in dsp_stream_id). */
+		if (spec->dsp_stream_id && s->stream_tag == spec->dsp_stream_id)
+			dsp = s;
+	}
+
+	s = dsp ? dsp : first;
+	if (s)
+		s->opened = 1;
+
+	return s;
+}
+
+/*
+ * Caller must hold spec->ae5_strip_mutex.
+ */
+static int ae5_strip_send_frame(struct hda_codec *codec, const u32 *grb_colors, int num_leds)
+{
+	struct ca0132_spec *spec = codec->spec;
+	struct hdac_bus *bus = &codec->bus->core;
+	struct snd_dma_buffer dmab;
+	struct hdac_stream *hstr = NULL;
+	unsigned int format, stream_tag;
+	u32 enc_words[4];
+	__le32 *dst;
+	int word_idx = 0;
+	int frame_words;
+	int led, w, i;
+	int retries = 20; /* ~100ms max */
+
+	if (!spec || !spec->mem_base)
+		return -ENODEV;
+	if (num_leds <= 0 || num_leds > AE5_STRIP_MAX_LEDS)
+		return -EINVAL;
+
+	lockdep_assert_held(&spec->ae5_strip_mutex);
+
+	CLASS(snd_hda_power_pm, pm)(codec);
+	if (pm.err < 0)
+		return pm.err;
+
+	/*
+	 * 44.1kHz, 24-bit, 2-channel format (0x4031) matches Windows CtxHda
+	 * HDAUDIO_STREAM_FORMAT.
+	 */
+	format = snd_hdac_stream_format(2, 24, 44100);
+
+	for (;;) {
+		hstr = ae5_strip_find_stream(codec);
+		if (!hstr) {
+			if (--retries <= 0) {
+				codec_warn(codec, "AE5 strip: no free azx stream after retries\n");
+				return -EBUSY;
+			}
+			usleep_range(5000, 10000);
+			continue;
+		}
+
+		stream_tag = snd_hdac_dsp_prepare(hstr, format, AE5_STRIP_DMA_SIZE, &dmab);
+		if ((int)stream_tag > 0)
+			break;
+
+		/* Prepare failed (e.g. -EBUSY due to race with playback starting); retry */
+		scoped_guard(spinlock_irq, &bus->reg_lock)
+			hstr->opened = 0;
+
+		if (--retries <= 0) {
+			codec_warn(codec, "AE5 strip: snd_hdac_dsp_prepare failed %d\n",
+				   (int)stream_tag);
+			return (int)stream_tag;
+		}
+		usleep_range(5000, 10000);
+	}
+
+	/* 1. Populate the 32KB DMA buffer with repeating WS2812 frames + reset gaps */
+	memset(dmab.area, 0, AE5_STRIP_DMA_SIZE);
+	dst = (__le32 *)dmab.area;
+
+	/* Words per frame: preamble + (num_leds * words_per_led) + reset gap */
+	frame_words = AE5_STRIP_PREAMBLE_WORDS + (num_leds * AE5_STRIP_WORDS_PER_LED) +
+		      AE5_STRIP_RESET_GAP_WORDS;
+
+	while (word_idx + frame_words <= AE5_STRIP_TOTAL_WORDS) {
+		/* Preamble per Windows CtxHda FUN_00042944 */
+		for (w = 0; w < AE5_STRIP_PREAMBLE_WORDS; w++) {
+			*dst++ = 0;
+			word_idx++;
+		}
+		/* LEDs */
+		for (led = 0; led < num_leds; led++) {
+			ae5_strip_encode_24(grb_colors[led], enc_words);
+			for (w = 0; w < AE5_STRIP_WORDS_PER_LED; w++) {
+				*dst++ = cpu_to_le32(enc_words[w]);
+				word_idx++;
+			}
+		}
+		/* Zero reset gap (> 1.8 ms; WS2812 requires > 50 us low) */
+		for (w = 0; w < AE5_STRIP_RESET_GAP_WORDS; w++) {
+			*dst++ = 0;
+			word_idx++;
+		}
+	}
+	while (word_idx < AE5_STRIP_TOTAL_WORDS) {
+		*dst++ = 0;
+		word_idx++;
+	}
+	/* Ensure DMA buffer writes are committed before triggering the HDA stream */
+	wmb();
+
+	/* 2. Configure CA0113 BAR2 hardware registers */
+	/* Power up clocks (CtxHdb 0x141b7 / 0x14210) */
+	writel(readl(spec->mem_base + 0xc04) | 0x7, spec->mem_base + 0xc04);
+
+	/* Base serializer initialization (CtxHdb 0x14ba4) */
+	writel(readl(spec->mem_base + 0x400) | 1, spec->mem_base + 0x400);
+	for (i = 0; i < 4; i++) {
+		writel(readl(CA0113_SERIALIZER_BASE(spec, i)) & ~1,
+		       CA0113_SERIALIZER_BASE(spec, i));
+		writel(0, CA0113_SERIALIZER_CLK(spec, i));
+	}
+	writel(readl(spec->mem_base + 0x408) | 1, spec->mem_base + 0x408);
+	writel(readl(spec->mem_base + 0x40c) | 1, spec->mem_base + 0x40c);
+	writel((readl(spec->mem_base + 0x410) & ~0xb) | 0x14, spec->mem_base + 0x410);
+
+	/* Configure serializers 0..3 clocking (CtxHdb 0x14a6c) */
+	for (i = 0; i < 4; i++)
+		writel(readl(CA0113_SERIALIZER_CLK(spec, i)) | 0x33,
+		       CA0113_SERIALIZER_CLK(spec, i));
+
+	/* BAR2 + 0x100 format & channel enables:
+	 * - base 0x70f
+	 * - bit 28 = 1 (24-bit audio format via CtxHdb 0x14f58)
+	 * - bits 29..31 = 1 (44.1 kHz sample rate via CtxHdb 0x14fa4)
+	 * - bits 4..7 = 0xf (stage 1 enables)
+	 * - bits 12..15 = 0xf (stage 2 enables)
+	 * => 0x3000ff8f
+	 */
+	writel((readl(spec->mem_base + 0x100) & ~0xe000ffff) | 0x3000ff8f, spec->mem_base + 0x100);
+
+	/* Enable serializer output drivers for pins 0..3 (CtxHdb 0x14e94) */
+	for (i = 0; i < 4; i++)
+		writel(readl(CA0113_SERIALIZER_OUT(spec, i)) | 1,
+		       CA0113_SERIALIZER_OUT(spec, i));
+
+	/* Route all channels 0..3 to stream_tag (CtxHdb 0x1502c) */
+	writel((stream_tag << 28) | (stream_tag << 20) | (stream_tag << 12) | (stream_tag << 4),
+	       spec->mem_base + 0x104);
+
+	/* Enable CA0113 MMIO GPIO 0 & 1 */
+	ca0113_mmio_gpio_set(codec, 0, true);
+	ca0113_mmio_gpio_set(codec, 1, true);
+
+	codec_dbg(codec, "AE5 strip: send_frame: num_leds=%d stream_tag=%u (0x%08x)\n",
+		  num_leds, stream_tag, readl(spec->mem_base + 0x104));
+
+	/* 3. Trigger stream transmission on HDA link */
+	snd_hdac_dsp_trigger(hstr, true);
+	/*
+	 * WS2812 latches on the >50us reset gap after one frame. The 32KB buffer holds ~64
+	 * repeating frame+reset cycles; at ~1.4ms/frame a 15ms run transmits ~10 complete
+	 * cycles - more than enough to latch reliably. Keep it short so rapid sysfs writes
+	 * (OpenRGB effects/theme changes) are not serialized behind a 1s blocking sleep.
+	 */
+	usleep_range(15000, 20000);
+	snd_hdac_dsp_trigger(hstr, false);
+	codec_dbg(codec, "AE5 strip: trigger complete\n");
+
+	/* Teardown: clear 0x104 pin mux back to 0 */
+	writel(0x00000000, spec->mem_base + 0x104);
+
+	snd_hdac_dsp_cleanup(hstr, &dmab);
+	scoped_guard(spinlock_irq, &bus->reg_lock)
+		hstr->opened = 0;
+
+	return 0;
+}
+
+static int ae5_strip_ctl_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
+	uinfo->count = AE5_STRIP_MAX_LEDS * 3;
+	return 0;
+}
+
+static int ae5_strip_ctl_get(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	int i;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	for (i = 0; i < spec->ae5_strip_cur_num_leds; i++) {
+		u32 grb = spec->ae5_strip_cur_colors[i];
+
+		ucontrol->value.bytes.data[i * 3 + 0] = (grb >> 8) & 0xff;
+		ucontrol->value.bytes.data[i * 3 + 1] = (grb >> 16) & 0xff;
+		ucontrol->value.bytes.data[i * 3 + 2] = grb & 0xff;
+	}
+	if (spec->ae5_strip_cur_num_leds < AE5_STRIP_MAX_LEDS)
+		memset(&ucontrol->value.bytes.data[spec->ae5_strip_cur_num_leds * 3], 0,
+		       (AE5_STRIP_MAX_LEDS - spec->ae5_strip_cur_num_leds) * 3);
+	return 0;
+}
+
+static int ae5_strip_ctl_put(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	u32 colors[AE5_STRIP_MAX_LEDS];
+	int i, num_leds, change, ret;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	num_leds = spec->ae5_strip_cur_num_leds;
+	for (i = 0; i < num_leds; i++) {
+		u8 r = ucontrol->value.bytes.data[i * 3 + 0];
+		u8 g = ucontrol->value.bytes.data[i * 3 + 1];
+		u8 b = ucontrol->value.bytes.data[i * 3 + 2];
+
+		colors[i] = ((u32)g << 16) | ((u32)r << 8) | (u32)b;
+	}
+	change = memcmp(spec->ae5_strip_cur_colors, colors,
+			sizeof(u32) * num_leds) != 0;
+	ret = ae5_strip_send_frame(codec, colors, num_leds);
+	if (ret < 0)
+		return ret;
+	if (change)
+		memcpy(spec->ae5_strip_cur_colors, colors,
+		       sizeof(u32) * num_leds);
+	return change;
+}
+
+static int ae5_strip_num_leds_info(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = 1;
+	uinfo->value.integer.max = AE5_STRIP_MAX_LEDS;
+	return 0;
+}
+
+static int ae5_strip_num_leds_get(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	ucontrol->value.integer.value[0] = spec->ae5_strip_cur_num_leds;
+	return 0;
+}
+
+static int ae5_strip_num_leds_put(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	int val = ucontrol->value.integer.value[0];
+	int ret;
+
+	if (val < 1 || val > AE5_STRIP_MAX_LEDS)
+		return -EINVAL;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	if (spec->ae5_strip_cur_num_leds == val)
+		return 0;
+	ret = ae5_strip_send_frame(codec, spec->ae5_strip_cur_colors, val);
+	if (ret < 0)
+		return ret;
+	spec->ae5_strip_cur_num_leds = val;
+	return 1;
+}
+
+static const struct snd_kcontrol_new ae5_strip_ctls[] = {
+	{
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.name = "AE-5 LED Strip",
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info = ae5_strip_ctl_info,
+		.get = ae5_strip_ctl_get,
+		.put = ae5_strip_ctl_put,
+	},
+	{
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.name = "AE-5 LED Strip Count",
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info = ae5_strip_num_leds_info,
+		.get = ae5_strip_num_leds_get,
+		.put = ae5_strip_num_leds_put,
+	},
+};
+
+static int ae5_add_strip_controls(struct hda_codec *codec)
+{
+	int i, err;
+
+	for (i = 0; i < ARRAY_SIZE(ae5_strip_ctls); i++) {
+		err = snd_hda_ctl_add(codec, 0,
+				      snd_ctl_new1(&ae5_strip_ctls[i], codec));
+		if (err < 0)
+			return err;
+	}
+	return 0;
+}
+#endif /* CONFIG_SND_HDA_DSP_LOADER */
+
 static void ae5_setup_defaults(struct hda_codec *codec)
 {
 	struct ca0132_spec *spec = codec->spec;
@@ -8741,6 +9126,10 @@ static void ca0132_init_chip(struct hda_codec *codec)
 	unsigned int on;
 
 	mutex_init(&spec->chipio_mutex);
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	mutex_init(&spec->ae5_strip_mutex);
+	spec->ae5_strip_cur_num_leds = 10;
+#endif
 
 	/*
 	 * The Windows driver always does this upon startup, which seems to
@@ -9626,6 +10015,9 @@ static void ca0132_free(struct hda_codec *codec)
 #ifdef CONFIG_PCI
 	if (spec->mem_base)
 		pci_iounmap(codec->bus->pci, spec->mem_base);
+#endif
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	mutex_destroy(&spec->ae5_strip_mutex);
 #endif
 	kfree(spec->spec_init_verbs);
 	kfree(codec->spec);
-- 
2.55.0

[PATCH v5] ALSA: hda/ca0132: Add Sound BlasterX AE-5 external RGB LED strip support

[Devin Christensen]

The Sound BlasterX AE-5 and AE-5 Plus expose a 3-pin 5V addressable RGB
header driven directly by the CA0113 PCIe-to-HD-Audio bridge. Rather
than using the CA0132 DSP or MMIO GPIO, the CA0113 contains an
autonomous HDA link sniffer that snoops a designated HDA DMA playback
stream, extracts the 24-bit GRB color payload, and serializes it as
800 kHz single-wire NRZ pulses to the strip (WS2812B protocol).

Expose the strip through volatile card control elements:

  "AE-5 LED Strip"        (RW, BYTES): 300-byte RGB payload representing
                          up to 100 addressable LEDs (3 bytes per LED).
  "AE-5 LED Strip Count"  (RW, INTEGER): Active LED count (1..100).

The controls are marked with IFACE_CARD and SNDRV_CTL_ELEM_ACCESS_VOLATILE
so changes do not trigger unnecessary audio daemon wakeups or state
restoration by alsactl.

Writes allocate an idle HDA playback stream, format a 32 KB DMA buffer
populated with repeating WS2812 frames (preamble, audio words per LED,
and reset gap), configure the CA0113 BAR2 serializers and stream-tag
pin mux, and pulse the stream long enough for the reset latch to fire.
Access is serialized with a per-spec mutex, and the controls are only
registered on QUIRK_AE5 devices.

The strip transport uses snd_hdac_dsp_prepare() / snd_hdac_dsp_cleanup(),
which require CONFIG_SND_HDA_DSP_LOADER. All strip-related code and struct
fields are conditionally compiled under
IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER), with a no-op stub for
ae5_add_strip_controls() when disabled.

Signed-off-by: Devin Christensen <dchristensen8@proton.me>
---
Updated to v5 to preserve colors across LED count changes:

- Parse, compare, and cache the full 100-LED payload (AE5_STRIP_MAX_LEDS)
  in ae5_strip_ctl_put() and ae5_strip_ctl_get(), passing only the active
  count to ae5_strip_send_frame(). This avoids discarding colors for
  inactive LEDs when userspace configures the strip before increasing
  the count.

Thanks,
Devin

v5:
 - Parse, compare, and cache the full 100-LED payload (AE5_STRIP_MAX_LEDS)
   in ae5_strip_ctl_put() and ae5_strip_ctl_get(), passing only the active
   count to ae5_strip_send_frame(). This preserves colors for inactive
   LEDs when userspace configures the strip before increasing the count.

v4:
 - Reserve HDA stream by marking s->opened = 1 under bus->reg_lock in
   ae5_strip_find_stream(), and clear on completion/error, preventing
   TOCTOU race with concurrent PCM stream assignment.
 - Check pm.err after CLASS(snd_hda_power_pm, pm)(codec) to avoid MMIO/DMA
   access on suspended or failed-to-resume devices.
 - Check return value of ae5_strip_send_frame() in control put callbacks,
   propagating errors to userspace and avoiding uncommitted state divergence.
 - Write DMA buffer words using cpu_to_le32() for big-endian architecture
   safety.
 - Remove redundant/overwritten orig_sd_ctl save and interrupt mask clearing.

v3:
 - Move #include <linux/dma-mapping.h> into main header block.
 - Check s->opened in ae5_strip_find_stream() to avoid stealing open streams.
 - Guard all strip code and struct members with IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
   and provide a static inline stub for ae5_add_strip_controls().
 - Return 1 from put callbacks when values change (using memcmp on colors).

v2:
 - Use CLASS(snd_hda_power_pm, pm)(codec) for RAII power management.
 - Switch userspace interface from sysfs to volatile card control elements
   ("AE-5 LED Strip" and "AE-5 LED Strip Count").

 sound/hda/codecs/ca0132.c | 391 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 390 insertions(+), 1 deletion(-)

diff --git a/sound/hda/codecs/ca0132.c b/sound/hda/codecs/ca0132.c
index 0f8fb62f0..896091c11 100644
--- a/sound/hda/codecs/ca0132.c
+++ b/sound/hda/codecs/ca0132.c
@@ -18,6 +18,7 @@
 #include <linux/types.h>
 #include <linux/io.h>
 #include <linux/pci.h>
+#include <linux/dma-mapping.h>
 #include <asm/io.h>
 #include <sound/core.h>
 #include <sound/hda_codec.h>
@@ -1060,6 +1061,8 @@ enum dsp_download_state {
  * CA0132 specific
  */
 
+#define AE5_STRIP_MAX_LEDS 100
+
 struct ca0132_spec {
 	struct hda_gen_spec gen;
 
@@ -1162,6 +1165,13 @@ struct ca0132_spec {
 	 * Renames PlayEnhancement and CrystalVoice too.
 	 */
 	bool use_alt_controls;
+
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	/* AE-5 WS2812 strip control */
+	struct mutex ae5_strip_mutex;
+	u32 ae5_strip_cur_colors[AE5_STRIP_MAX_LEDS];
+	int ae5_strip_cur_num_leds;
+#endif
 };
 
 /*
@@ -6846,6 +6856,15 @@ static int ca0132_alt_add_mic_boost_enum(struct hda_codec *codec)
 
 }
 
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+static int ae5_add_strip_controls(struct hda_codec *codec);
+#else
+static inline int ae5_add_strip_controls(struct hda_codec *codec)
+{
+	return 0;
+}
+#endif
+
 /*
  * Add headphone gain enumerated control for the AE-5. This switches between
  * three modes, low, medium, and high. When non-headphone outputs are selected,
@@ -7149,6 +7168,10 @@ static int ca0132_build_controls(struct hda_codec *codec)
 
 	switch (ca0132_quirk(spec)) {
 	case QUIRK_AE5:
+		err = ae5_add_strip_controls(codec);
+		if (err < 0)
+			return err;
+		fallthrough;
 	case QUIRK_AE7:
 		err = ae5_add_headphone_gain_enum(codec);
 		if (err < 0)
@@ -8316,8 +8339,367 @@ static void sbz_setup_defaults(struct hda_codec *codec)
 }
 
 /*
- * Setup default parameters for the Sound BlasterX AE-5 DSP.
+ * Sound BlasterX AE-5 External WS2812B RGB LED Strip Transport
  */
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+#define AE5_STRIP_DMA_SIZE		0x8000
+#define AE5_STRIP_TOTAL_WORDS		(AE5_STRIP_DMA_SIZE / sizeof(u32))
+#define AE5_STRIP_PREAMBLE_WORDS	5
+#define AE5_STRIP_WORDS_PER_LED		4
+#define AE5_STRIP_RESET_GAP_WORDS	83
+
+#define CA0113_SERIALIZER_BASE(spec, ch)	((spec)->mem_base + 0x42c + (ch) * 0x40)
+#define CA0113_SERIALIZER_CLK(spec, ch)		((spec)->mem_base + 0x43c + (ch) * 0x40)
+#define CA0113_SERIALIZER_OUT(spec, ch)		((spec)->mem_base + 0x454 + (ch) * 0x40)
+
+static void ae5_strip_encode_24(u32 u, u32 *words)
+{
+	/*
+	 * 24-bit pixel -> 4 x 32-bit audio words (6 bits per word).
+	 * Hardware audio serializer transmits MSB first (bits 31 down to 0).
+	 * For word i (i8 = 23, 17, 11, 5), bit_idx 0..5 (MSB to LSB within the word)
+	 * is placed at n = 29 - bit_idx * 4:
+	 *   Bit 0 -> 0b100 << n (375ns high, 1042ns low): BIT(n + 2)
+	 *   Bit 1 -> 0b111 << n (1083ns high, 333ns low): BIT(n + 2) | BIT(n + 1) | BIT(n)
+	 */
+	int i8 = 23;
+	int i, bit_idx;
+
+	for (i = 0; i < 4; i++) {
+		u32 out = 0;
+
+		for (bit_idx = 0; bit_idx < 6; bit_idx++) {
+			int bit = (u >> (i8 - bit_idx)) & 1;
+			int n = 29 - bit_idx * 4;
+
+			out |= (bit ? (BIT(2) | BIT(1) | BIT(0)) : BIT(2)) << n;
+		}
+		words[i] = out;
+		i8 -= 6;
+	}
+}
+
+static struct hdac_stream *ae5_strip_find_stream(struct hda_codec *codec)
+{
+	struct ca0132_spec *spec = codec->spec;
+	struct hdac_bus *bus = &codec->bus->core;
+	struct hdac_stream *s, *dsp = NULL, *first = NULL;
+
+	guard(spinlock_irqsave)(&bus->reg_lock);
+	list_for_each_entry(s, &bus->stream_list, list) {
+		if (s->direction != SNDRV_PCM_STREAM_PLAYBACK)
+			continue;
+		if (s->opened || s->running || s->locked)
+			continue;
+		if (!first)
+			first = s;
+		/* The DSP DMA consumes the DSP-loader stream (tag in dsp_stream_id). */
+		if (spec->dsp_stream_id && s->stream_tag == spec->dsp_stream_id)
+			dsp = s;
+	}
+
+	s = dsp ? dsp : first;
+	if (s)
+		s->opened = 1;
+
+	return s;
+}
+
+/*
+ * Caller must hold spec->ae5_strip_mutex.
+ */
+static int ae5_strip_send_frame(struct hda_codec *codec, const u32 *grb_colors, int num_leds)
+{
+	struct ca0132_spec *spec = codec->spec;
+	struct hdac_bus *bus = &codec->bus->core;
+	struct snd_dma_buffer dmab;
+	struct hdac_stream *hstr = NULL;
+	unsigned int format, stream_tag;
+	u32 enc_words[4];
+	__le32 *dst;
+	int word_idx = 0;
+	int frame_words;
+	int led, w, i;
+	int retries = 20; /* ~100ms max */
+
+	if (!spec || !spec->mem_base)
+		return -ENODEV;
+	if (num_leds <= 0 || num_leds > AE5_STRIP_MAX_LEDS)
+		return -EINVAL;
+
+	lockdep_assert_held(&spec->ae5_strip_mutex);
+
+	CLASS(snd_hda_power_pm, pm)(codec);
+	if (pm.err < 0)
+		return pm.err;
+
+	/*
+	 * 44.1kHz, 24-bit, 2-channel format (0x4031) matches Windows CtxHda
+	 * HDAUDIO_STREAM_FORMAT.
+	 */
+	format = snd_hdac_stream_format(2, 24, 44100);
+
+	for (;;) {
+		hstr = ae5_strip_find_stream(codec);
+		if (!hstr) {
+			if (--retries <= 0) {
+				codec_warn(codec, "AE5 strip: no free azx stream after retries\n");
+				return -EBUSY;
+			}
+			usleep_range(5000, 10000);
+			continue;
+		}
+
+		stream_tag = snd_hdac_dsp_prepare(hstr, format, AE5_STRIP_DMA_SIZE, &dmab);
+		if ((int)stream_tag > 0)
+			break;
+
+		/* Prepare failed (e.g. -EBUSY due to race with playback starting); retry */
+		scoped_guard(spinlock_irq, &bus->reg_lock)
+			hstr->opened = 0;
+
+		if (--retries <= 0) {
+			codec_warn(codec, "AE5 strip: snd_hdac_dsp_prepare failed %d\n",
+				   (int)stream_tag);
+			return (int)stream_tag;
+		}
+		usleep_range(5000, 10000);
+	}
+
+	/* 1. Populate the 32KB DMA buffer with repeating WS2812 frames + reset gaps */
+	memset(dmab.area, 0, AE5_STRIP_DMA_SIZE);
+	dst = (__le32 *)dmab.area;
+
+	/* Words per frame: preamble + (num_leds * words_per_led) + reset gap */
+	frame_words = AE5_STRIP_PREAMBLE_WORDS + (num_leds * AE5_STRIP_WORDS_PER_LED) +
+		      AE5_STRIP_RESET_GAP_WORDS;
+
+	while (word_idx + frame_words <= AE5_STRIP_TOTAL_WORDS) {
+		/* Preamble per Windows CtxHda FUN_00042944 */
+		for (w = 0; w < AE5_STRIP_PREAMBLE_WORDS; w++) {
+			*dst++ = 0;
+			word_idx++;
+		}
+		/* LEDs */
+		for (led = 0; led < num_leds; led++) {
+			ae5_strip_encode_24(grb_colors[led], enc_words);
+			for (w = 0; w < AE5_STRIP_WORDS_PER_LED; w++) {
+				*dst++ = cpu_to_le32(enc_words[w]);
+				word_idx++;
+			}
+		}
+		/* Zero reset gap (> 1.8 ms; WS2812 requires > 50 us low) */
+		for (w = 0; w < AE5_STRIP_RESET_GAP_WORDS; w++) {
+			*dst++ = 0;
+			word_idx++;
+		}
+	}
+	while (word_idx < AE5_STRIP_TOTAL_WORDS) {
+		*dst++ = 0;
+		word_idx++;
+	}
+	/* Ensure DMA buffer writes are committed before triggering the HDA stream */
+	wmb();
+
+	/* 2. Configure CA0113 BAR2 hardware registers */
+	/* Power up clocks (CtxHdb 0x141b7 / 0x14210) */
+	writel(readl(spec->mem_base + 0xc04) | 0x7, spec->mem_base + 0xc04);
+
+	/* Base serializer initialization (CtxHdb 0x14ba4) */
+	writel(readl(spec->mem_base + 0x400) | 1, spec->mem_base + 0x400);
+	for (i = 0; i < 4; i++) {
+		writel(readl(CA0113_SERIALIZER_BASE(spec, i)) & ~1,
+		       CA0113_SERIALIZER_BASE(spec, i));
+		writel(0, CA0113_SERIALIZER_CLK(spec, i));
+	}
+	writel(readl(spec->mem_base + 0x408) | 1, spec->mem_base + 0x408);
+	writel(readl(spec->mem_base + 0x40c) | 1, spec->mem_base + 0x40c);
+	writel((readl(spec->mem_base + 0x410) & ~0xb) | 0x14, spec->mem_base + 0x410);
+
+	/* Configure serializers 0..3 clocking (CtxHdb 0x14a6c) */
+	for (i = 0; i < 4; i++)
+		writel(readl(CA0113_SERIALIZER_CLK(spec, i)) | 0x33,
+		       CA0113_SERIALIZER_CLK(spec, i));
+
+	/* BAR2 + 0x100 format & channel enables:
+	 * - base 0x70f
+	 * - bit 28 = 1 (24-bit audio format via CtxHdb 0x14f58)
+	 * - bits 29..31 = 1 (44.1 kHz sample rate via CtxHdb 0x14fa4)
+	 * - bits 4..7 = 0xf (stage 1 enables)
+	 * - bits 12..15 = 0xf (stage 2 enables)
+	 * => 0x3000ff8f
+	 */
+	writel((readl(spec->mem_base + 0x100) & ~0xe000ffff) | 0x3000ff8f, spec->mem_base + 0x100);
+
+	/* Enable serializer output drivers for pins 0..3 (CtxHdb 0x14e94) */
+	for (i = 0; i < 4; i++)
+		writel(readl(CA0113_SERIALIZER_OUT(spec, i)) | 1,
+		       CA0113_SERIALIZER_OUT(spec, i));
+
+	/* Route all channels 0..3 to stream_tag (CtxHdb 0x1502c) */
+	writel((stream_tag << 28) | (stream_tag << 20) | (stream_tag << 12) | (stream_tag << 4),
+	       spec->mem_base + 0x104);
+
+	/* Enable CA0113 MMIO GPIO 0 & 1 */
+	ca0113_mmio_gpio_set(codec, 0, true);
+	ca0113_mmio_gpio_set(codec, 1, true);
+
+	codec_dbg(codec, "AE5 strip: send_frame: num_leds=%d stream_tag=%u (0x%08x)\n",
+		  num_leds, stream_tag, readl(spec->mem_base + 0x104));
+
+	/* 3. Trigger stream transmission on HDA link */
+	snd_hdac_dsp_trigger(hstr, true);
+	/*
+	 * WS2812 latches on the >50us reset gap after one frame. The 32KB buffer holds ~64
+	 * repeating frame+reset cycles; at ~1.4ms/frame a 15ms run transmits ~10 complete
+	 * cycles - more than enough to latch reliably. Keep it short so rapid sysfs writes
+	 * (OpenRGB effects/theme changes) are not serialized behind a 1s blocking sleep.
+	 */
+	usleep_range(15000, 20000);
+	snd_hdac_dsp_trigger(hstr, false);
+	codec_dbg(codec, "AE5 strip: trigger complete\n");
+
+	/* Teardown: clear 0x104 pin mux back to 0 */
+	writel(0x00000000, spec->mem_base + 0x104);
+
+	snd_hdac_dsp_cleanup(hstr, &dmab);
+	scoped_guard(spinlock_irq, &bus->reg_lock)
+		hstr->opened = 0;
+
+	return 0;
+}
+
+static int ae5_strip_ctl_info(struct snd_kcontrol *kcontrol,
+			      struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
+	uinfo->count = AE5_STRIP_MAX_LEDS * 3;
+	return 0;
+}
+
+static int ae5_strip_ctl_get(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	int i;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	for (i = 0; i < AE5_STRIP_MAX_LEDS; i++) {
+		u32 grb = spec->ae5_strip_cur_colors[i];
+
+		ucontrol->value.bytes.data[i * 3 + 0] = (grb >> 8) & 0xff;
+		ucontrol->value.bytes.data[i * 3 + 1] = (grb >> 16) & 0xff;
+		ucontrol->value.bytes.data[i * 3 + 2] = grb & 0xff;
+	}
+	return 0;
+}
+
+static int ae5_strip_ctl_put(struct snd_kcontrol *kcontrol,
+			     struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	u32 colors[AE5_STRIP_MAX_LEDS];
+	int i, num_leds, change, ret;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	for (i = 0; i < AE5_STRIP_MAX_LEDS; i++) {
+		u8 r = ucontrol->value.bytes.data[i * 3 + 0];
+		u8 g = ucontrol->value.bytes.data[i * 3 + 1];
+		u8 b = ucontrol->value.bytes.data[i * 3 + 2];
+
+		colors[i] = ((u32)g << 16) | ((u32)r << 8) | (u32)b;
+	}
+	change = memcmp(spec->ae5_strip_cur_colors, colors,
+			sizeof(spec->ae5_strip_cur_colors)) != 0;
+	num_leds = spec->ae5_strip_cur_num_leds;
+	ret = ae5_strip_send_frame(codec, colors, num_leds);
+	if (ret < 0)
+		return ret;
+	if (change)
+		memcpy(spec->ae5_strip_cur_colors, colors,
+		       sizeof(spec->ae5_strip_cur_colors));
+	return change;
+}
+
+static int ae5_strip_num_leds_info(struct snd_kcontrol *kcontrol,
+				   struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 1;
+	uinfo->value.integer.min = 1;
+	uinfo->value.integer.max = AE5_STRIP_MAX_LEDS;
+	return 0;
+}
+
+static int ae5_strip_num_leds_get(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	ucontrol->value.integer.value[0] = spec->ae5_strip_cur_num_leds;
+	return 0;
+}
+
+static int ae5_strip_num_leds_put(struct snd_kcontrol *kcontrol,
+				  struct snd_ctl_elem_value *ucontrol)
+{
+	struct hda_codec *codec = snd_kcontrol_chip(kcontrol);
+	struct ca0132_spec *spec = codec->spec;
+	int val = ucontrol->value.integer.value[0];
+	int ret;
+
+	if (val < 1 || val > AE5_STRIP_MAX_LEDS)
+		return -EINVAL;
+
+	guard(mutex)(&spec->ae5_strip_mutex);
+	if (spec->ae5_strip_cur_num_leds == val)
+		return 0;
+	ret = ae5_strip_send_frame(codec, spec->ae5_strip_cur_colors, val);
+	if (ret < 0)
+		return ret;
+	spec->ae5_strip_cur_num_leds = val;
+	return 1;
+}
+
+static const struct snd_kcontrol_new ae5_strip_ctls[] = {
+	{
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.name = "AE-5 LED Strip",
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info = ae5_strip_ctl_info,
+		.get = ae5_strip_ctl_get,
+		.put = ae5_strip_ctl_put,
+	},
+	{
+		.iface = SNDRV_CTL_ELEM_IFACE_CARD,
+		.name = "AE-5 LED Strip Count",
+		.access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
+			  SNDRV_CTL_ELEM_ACCESS_VOLATILE,
+		.info = ae5_strip_num_leds_info,
+		.get = ae5_strip_num_leds_get,
+		.put = ae5_strip_num_leds_put,
+	},
+};
+
+static int ae5_add_strip_controls(struct hda_codec *codec)
+{
+	int i, err;
+
+	for (i = 0; i < ARRAY_SIZE(ae5_strip_ctls); i++) {
+		err = snd_hda_ctl_add(codec, 0,
+				      snd_ctl_new1(&ae5_strip_ctls[i], codec));
+		if (err < 0)
+			return err;
+	}
+	return 0;
+}
+#endif /* CONFIG_SND_HDA_DSP_LOADER */
+
 static void ae5_setup_defaults(struct hda_codec *codec)
 {
 	struct ca0132_spec *spec = codec->spec;
@@ -8741,6 +9123,10 @@ static void ca0132_init_chip(struct hda_codec *codec)
 	unsigned int on;
 
 	mutex_init(&spec->chipio_mutex);
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	mutex_init(&spec->ae5_strip_mutex);
+	spec->ae5_strip_cur_num_leds = 10;
+#endif
 
 	/*
 	 * The Windows driver always does this upon startup, which seems to
@@ -9626,6 +10012,9 @@ static void ca0132_free(struct hda_codec *codec)
 #ifdef CONFIG_PCI
 	if (spec->mem_base)
 		pci_iounmap(codec->bus->pci, spec->mem_base);
+#endif
+#if IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER)
+	mutex_destroy(&spec->ae5_strip_mutex);
 #endif
 	kfree(spec->spec_init_verbs);
 	kfree(codec->spec);
-- 
2.55.0

Re: [PATCH v5] ALSA: hda/ca0132: Add Sound BlasterX AE-5 external RGB LED strip support

[Takashi Iwai]

On Wed, 07 Oct 2026 18:32:14 +0200,
Devin Christensen wrote:
> 
> The Sound BlasterX AE-5 and AE-5 Plus expose a 3-pin 5V addressable RGB
> header driven directly by the CA0113 PCIe-to-HD-Audio bridge. Rather
> than using the CA0132 DSP or MMIO GPIO, the CA0113 contains an
> autonomous HDA link sniffer that snoops a designated HDA DMA playback
> stream, extracts the 24-bit GRB color payload, and serializes it as
> 800 kHz single-wire NRZ pulses to the strip (WS2812B protocol).
> 
> Expose the strip through volatile card control elements:
> 
>   "AE-5 LED Strip"        (RW, BYTES): 300-byte RGB payload representing
>                           up to 100 addressable LEDs (3 bytes per LED).
>   "AE-5 LED Strip Count"  (RW, INTEGER): Active LED count (1..100).
> 
> The controls are marked with IFACE_CARD and SNDRV_CTL_ELEM_ACCESS_VOLATILE
> so changes do not trigger unnecessary audio daemon wakeups or state
> restoration by alsactl.
> 
> Writes allocate an idle HDA playback stream, format a 32 KB DMA buffer
> populated with repeating WS2812 frames (preamble, audio words per LED,
> and reset gap), configure the CA0113 BAR2 serializers and stream-tag
> pin mux, and pulse the stream long enough for the reset latch to fire.
> Access is serialized with a per-spec mutex, and the controls are only
> registered on QUIRK_AE5 devices.
> 
> The strip transport uses snd_hdac_dsp_prepare() / snd_hdac_dsp_cleanup(),
> which require CONFIG_SND_HDA_DSP_LOADER. All strip-related code and struct
> fields are conditionally compiled under
> IS_ENABLED(CONFIG_SND_HDA_DSP_LOADER), with a no-op stub for
> ae5_add_strip_controls() when disabled.
> 
> Signed-off-by: Devin Christensen <dchristensen8@proton.me>

Applied now to for-next branch.  Thanks.


Takashi