Re: [REPORT] ALSA: hda/realtek: Fix silent/extremely quiet audio on HP Pavilion x360 (ALC295) with uninitialized SSID 103c:0000

[Takashi Iwai <tiwai@suse.de>]

On Sun, 01 Mar 2026 06:57:31 +0100,
Ngon wrote:
> 
> 
> Hi Takashi and ALSA developers,
> 
>   I would like to report a hardware quirk and a verified fix for the
> HP Pavilion x360 Convertible 14-cd0xxx (Codec:
>   Realtek ALC295).
> 
>   Problem:
>   The BIOS on this model reports a generic/uninitialized Subsystem ID:
> 103c:0000. Because of this, the kernel fails to
>   apply the necessary HP-specific quirks. The audio output is either
> completely silent or extremely quiet, even when all
>   mixers are at 100%. This issue is particularly severe on machines
> where the original screen has been removed/modified,
>   which seems to trigger a "protection mode" in the hardware
> amplifier.
> 
>   Hardware Details:
>    - Model: HP Pavilion x360 Convertible 14-cd0xxx
>    - Codec: Realtek ALC295
>    - Reported Subsystem ID: 103c:0000

This SSID with 0 is a problem.  0 is used for a wild card matching,
hence it won't match properly.

I suppose the above is PCI SSID, and the codec SSID is a valid number?
You can see it in the proc output.

>   The Fix:
>   I found that manually forcing the amplifier gain and processing
> coefficients using hda-verb restores the audio to
>   normal volume levels. The following verbs are required:
> 
>    1. hda-verb /dev/snd/hwC0D0 0x20 SET_COEF_INDEX 0x07 followed by
> SET_PROC_COEF 0x7770 (Forces Amplifier Gain)
>    2. hda-verb /dev/snd/hwC0D0 0x20 SET_COEF_INDEX 0x0d followed by
> SET_PROC_COEF 0x3000 (Sets Processing State)
> 
>   Proposed Solution:
>   Could these verbs be integrated as a default quirk for ALC295 when
> the Subsystem ID 103c:0000 is detected on HP
>   hardware?

If a codec SSID has valid numbers, you can put a quick entry with
HDA_CODEC_QUIRK() instead of SND_PCI_QUIRK().

> Or perhaps added to the ALC269_FIXUP_HP_GPIO_LED chain?

Depends on the hardware implementation :)
If the GPIO LED control works with that quirk, you should chain it,
indeed.

>   I have verified this fix on Pop!_OS 22.04 (Kernel 6.17) and it
> consistently solves the issue.

In anyway, could you give alsa-info.sh output?  Run the script with
--no-upload option, and attach the output.

Also, please rather post to linux-sound@vger.kernel.org instead of
alsa-devel ML.  It's a better place for tracking the kernel issue (and
the patches).


thanks,

Takashi