Re: [PATCH] ALSA: hda/realtek: Enable PC beep passthrough for HP EliteBook 855 G7

["Maciej S. Szmigiero" <mail@xxxxxxxxxxxxxxxxxxxxx>]

On 12.01.2025 13:11, Takashi Iwai wrote:
> On Wed, 01 Jan 2025 14:16:05 +0100,
> Maciej S. Szmigiero wrote:
> > PC speaker works well on this platform in BIOS and in Linux until sound
> > card drivers are loaded. Then it stops working.
> >
> > There seems to be a beep generator node at 0x1a in this CODEC
> > (ALC269_TYPE_ALC215) but it seems to be only connected to capture mixers
> > at nodes 0x22 and 0x23.
> > If I unmute the mixer input for 0x1a at node 0x23 and start recording
> > from its "ALC285 Analog" capture device I can clearly hear beeps in that
> > recording.
> >
> > So the beep generator is indeed working properly, however I wasn't able to
> > figure out any way to connect it to speakers.
> >
> > However, the bits in the "Passthrough Control" register (0x36) seems to
> > work at least partially: by zeroing "B" and "h" and setting "S" I can at
> > least make the PIT PC speaker output appear either in this laptop speakers
> > or headphones (depending on whether they are connected or not).
> >
> >
> > There are some caveats, however:
> > * If the CODEC gets runtime-suspended the beeps stop so it needs HDA beep
> > device for keeping it awake during beeping.
> >
> > * If the beep generator node is generating any beep the PC beep passthrough
> > seems to be temporarily inhibited, so the HDA beep device has to be
> > prevented from using the actual beep generator node - but the beep device
> > is still necessary due to the previous point.
> >
> > * In contrast with other platforms here beep amplification has to be
> > disabled otherwise the beeps output are WAY louder than they were on pure
> > BIOS setup.
> >
> >
> > Unless someone (from Realtek probably) knows how to make the beep generator
> > node output appear in speakers / headphones using PC beep passthrough seems
> > to be the only way to make PC speaker beeping actually work on this
> > platform.
> >
> > Signed-off-by: Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>
>
> It's a change that does handle things completely differently from the
> current implementation, and it uses undocumented Realtek-specific
> things, so I'd rather want comments from Realtek.
>
> Kailang, is this feature correct and can be used safely?

...and if it is incorrect then it would be nice to know how to do it
the correct way.

By the way, the patch will need a respin anyway to correct the typo in
!IS_ENABLED(CONFIG_INPUT_PCSPKR) code that the kernel test robot found
and to change that codec_warn() into dev_warn_once(hda_codec_dev(codec))
to avoid spamming the kernel log at runtime PM CODEC re-init.

> thanks,
>
> Takashi

Thanks,
Maciej