[PATCH] ALSA: hda/realtek: Add mute LED quirk for HP Laptop 15-fd2xxx

[Preston Lam <plamlam99@gmail.com>]

The HP Laptop 15-fd2xxx (PCI SSID 103c:8e43, Realtek ALC236) has a
speaker mute LED on the F5 key and a microphone mute LED on the F8 key.
Neither lights up, because the model has no quirk entry and only the
generic HP vendor fallback (ALC269_FIXUP_HP_MUTE_LED) is applied.

Probing the codec with hda-verb showed how the LEDs are wired:

 - mute LED: COEF index 0x07, bit 0, on NID 0x20 (set = LED on)
 - mic mute LED: codec GPIO0, active low (driven low = LED on)

Driving GPIO1 and GPIO2 did not light the mute LED. This wiring is
exactly what the existing ALC236_FIXUP_HP_MUTE_LED_MICMUTE_GPIO fixup
implements (COEF 0x07 bit 0 for the mute LED, GPIO0 with inverted
polarity for the micmute LED), so use it for this model. The sibling
HP Laptop 15-fd0xxx (103c:8dd7) already uses the same fixup.

Tested on this machine running Ubuntu 7.0.0-34-generic (SOF driver, the
quirk built into snd-hda-codec-alc269 from Ubuntu's 7.0.0-34.34 source
tree): the hda::mute and hda::micmute LEDs are created, follow the
Master mute state and the Dmic0 capture switch respectively, and the
F5 and F8 keys toggle them correctly. Muting the microphone also
silences the capture stream. The LEDs also kept the correct state across
an s2idle suspend/resume cycle (speaker muted in one run, microphone in
another) and still responded to mute changes afterwards; long suspends
were not tested. The desktop session was SwayFX (wlroots) with PipeWire,
which only changes the mute state through the normal mixer controls; no
other desktop was tried. Not tested on a mainline kernel tree directly;
the change is only the quirk table entry.

AI assistance: this patch, the hardware analysis behind it (probing the
codec with hda-verb and choosing the existing fixup) and this commit
message were written by Claude Code (Anthropic, model claude-sonnet-5-5).
The submitter ran the privileged commands and reboots and reported the
LED behavior; Claude Code ran the tests and read the kernel logs.

Assisted-by: Claude:claude-sonnet-5-5
Signed-off-by: Preston Lam <plamlam99@gmail.com>
---
 sound/hda/codecs/realtek/alc269.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/hda/codecs/realtek/alc269.c b/sound/hda/codecs/realtek/alc269.c
index 13bc74190..caf1b801f 100644
--- a/sound/hda/codecs/realtek/alc269.c
+++ b/sound/hda/codecs/realtek/alc269.c
@@ -7847,6 +7847,7 @@ static const struct hda_quirk alc269_fixup_tbl[] = {
 	SND_PCI_QUIRK(0x103c, 0x8e37, "HP 16 Piston OmniBook X", ALC287_FIXUP_CS35L41_I2C_2),
 	SND_PCI_QUIRK(0x103c, 0x8e3a, "HP Agusta", ALC287_FIXUP_CS35L41_I2C_2),
 	SND_PCI_QUIRK(0x103c, 0x8e3b, "HP Agusta", ALC287_FIXUP_CS35L41_I2C_2),
+	SND_PCI_QUIRK(0x103c, 0x8e43, "HP Laptop 15-fd2xxx", ALC236_FIXUP_HP_MUTE_LED_MICMUTE_GPIO),
 	SND_PCI_QUIRK(0x103c, 0x8e60, "HP OmniBook 7 Laptop 16-bh0xxx", ALC245_FIXUP_CS35L41_I2C_2_MUTE_LED),
 	SND_PCI_QUIRK(0x103c, 0x8e61, "HP Trekker ", ALC287_FIXUP_CS35L41_I2C_2),
 	SND_PCI_QUIRK(0x103c, 0x8e62, "HP Trekker ", ALC287_FIXUP_CS35L41_I2C_2),
-- 
2.53.0