[RFC PATCH] ALSA: hda/intel: Disable power saving on ASUS GU605CX

[Suzu <suzu1dev@gmail.com>]

On the ASUS ROG Zephyrus G16 GU605CX, the ALC285 analog headphone
output produces a loud pop about ten seconds after playback stops
with power_save=10. This was reproduced with iLoud Micro Monitor
powered speakers connected to the 3.5 mm jack. Setting power_save=0
eliminated the idle pops in repeated pause/resume tests on
7.2.3-arch1-2, with power_save_controller left enabled.

Extend the power-save denylist check to cover the tested Intel HDA
controller (8086:7728, subsystem 1043:1034) on this board. Check the
DMI board vendor and name as well, since GU605CW also uses subsystem
1043:1034 and has not been tested for this issue. Keep the existing
pm_blacklist override behavior.

Disabling idle power saving can increase idle power consumption on
the matched controller. A separate pop during shutdown was still
observed with power_save=0; this change does not address it.

Link: https://github.com/omacom/omarchy/pull/10498
Assisted-by: LLM
Signed-off-by: Suzu <suzu1dev@gmail.com>
---
Validation completed on the affected GU605CX:
- Built and booted the complete patched 7.3-rc1 kernel; the native
  kernel build log contains no warnings.
- Verified that the loaded HDA module's srcversion matches the built
  artifact for 7.3.0-rc1-audio-pop-test.
- Confirmed power_save=10, power_save_controller=Y and pm_blacklist=-1,
  with the expected 1043:1034 power-save denylist message.
- In five samples spanning 40 seconds, the Intel analog PipeWire sink
  was SUSPENDED while the ALC285 remained runtime-active with
  power/control=on. This was sampled observation, not continuous tracing.
- Intel and NVIDIA HDMI codecs were observed suspended with
  power/control=auto; the NVIDIA HDA controller was also suspended.
- After booting this kernel and receiving the pause/resume test
  instructions, the user confirmed that the popping was no longer
  audible. The exact number of cycles and pause durations were not
  separately reported for this patched-kernel test.
- The earlier power_save=0 workaround also passed human pause/resume
  listening tests on 7.2.3-arch1-2, with controller power saving enabled.

Headphone switching, internal speakers and suspend/resume checks have
not been reported for this patched kernel. Boot-time popping remains
unverified. A shutdown pop was previously observed with power_save=0;
this change does not address that shutdown path. No reliable measurement
of additional idle power consumption is available.

Test-build context: an Arch-derived configuration with debug information
and BTF disabled was used. NVIDIA 610.57.04 test modules required a
separate local adaptation for the 7.3 dmem cgroup registration API.
Those modules built and initialized; their objtool return warnings also
occurred in the production-driver build. The NVIDIA adaptation is not
part of this audio patch. Full graphics regression testing was not done.

AI assistance: I asked OpenAI Codex to investigate the idle pops
and prepare a GU605CX-specific fix. It assisted with the patch,
changelog and build/runtime checks. I performed the listening
tests; results are described above. I booted the patched kernel
and confirmed that the idle pop was no longer audible.

No introducing commit has been identified, so no Fixes tag is proposed.

 sound/hda/controllers/intel.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/sound/hda/controllers/intel.c b/sound/hda/controllers/intel.c
index 24015c73a..6da1d7ee5 100644
--- a/sound/hda/controllers/intel.c
+++ b/sound/hda/controllers/intel.c
@@ -2328,18 +2328,30 @@ static const struct snd_pci_quirk power_save_denylist[] = {
 	{}
 };
 
+static bool azx_is_power_save_denylisted(struct pci_dev *pci)
+{
+	if (snd_pci_quirk_lookup(pci, power_save_denylist))
+		return true;
+
+	/* GU605CW shares the subsystem ID; only GU605CX was tested. */
+	return pci->vendor == PCI_VENDOR_ID_INTEL &&
+	       pci->device == PCI_DEVICE_ID_INTEL_HDA_ARL &&
+	       pci->subsystem_vendor == 0x1043 &&
+	       pci->subsystem_device == 0x1034 &&
+	       dmi_match(DMI_BOARD_VENDOR, "ASUSTeK COMPUTER INC.") &&
+	       dmi_match(DMI_BOARD_NAME, "GU605CX");
+}
+
 static void set_default_power_save(struct azx *chip)
 {
 	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
 	int val = power_save;
 
 	if (pm_blacklist < 0) {
-		const struct snd_pci_quirk *q;
-
-		q = snd_pci_quirk_lookup(chip->pci, power_save_denylist);
-		if (q && val) {
+		if (val && azx_is_power_save_denylisted(chip->pci)) {
 			dev_info(chip->card->dev, "device %04x:%04x is on the power_save denylist, forcing power_save to 0\n",
-				 q->subvendor, q->subdevice);
+				 chip->pci->subsystem_vendor,
+				 chip->pci->subsystem_device);
 			val = 0;
 			hda->runtime_pm_disabled = 1;
 		}

base-commit: 45b5beb60bf7bd41c55ef17f6f2d28b351fad6c0
-- 
2.55.0