linux-kernel - Re: [PATCH v2] ALSA: hda: Continue to probe when codec probe fails

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Message-ID: <s5h5z51oj12.wl-tiwai@suse.de>
Date:   Wed, 16 Dec 2020 16:41:29 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     tiwai@...e.com, Jaroslav Kysela <perex@...ex.cz>,
        Kai Vehmanen <kai.vehmanen@...ux.intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Alex Deucher <alexander.deucher@....com>,
        Mike Rapoport <rppt@...nel.org>,
        alsa-devel@...a-project.org (moderated list:SOUND),
        linux-kernel@...r.kernel.org (open list)
Subject: Re: [PATCH v2] ALSA: hda: Continue to probe when codec probe fails

On Wed, 16 Dec 2020 13:47:24 +0100,
Kai-Heng Feng wrote:
> 
> Similar to commit 9479e75fca37 ("ALSA: hda: Keep the controller
> initialization even if no codecs found"), when codec probe fails, it
> doesn't enable runtime suspend, and can prevent graphics card from
> getting powered down:
> [    4.280991] snd_hda_intel 0000:01:00.1: no codecs initialized
> 
> $ cat /sys/bus/pci/devices/0000:01:00.1/power/runtime_status
> active
> 
> So mark there's no codec and continue probing to let runtime PM to work.
> 
> BugLink: https://bugs.launchpad.net/bugs/1907212
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>

Hm, but if the probe fails, doesn't it mean something really wrong?
IOW, how does this situation happen?

The usual no-codec state is for the devices that have a bogus HD-audio
bus remaining while codecs aren't hooked or disabled by BIOS.  For
that, it makes to leave the controller driver and let it idle.  But if
you get really an error, it's something to fix there, not to just
ignore in general.


thanks,

Takashi

> ---
>  sound/pci/hda/hda_intel.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 6852668f1bcb..872a703dee43 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -2328,7 +2328,7 @@ static int azx_probe_continue(struct azx *chip)
>  	if (bus->codec_mask) {
>  		err = azx_probe_codecs(chip, azx_max_codecs[chip->driver_type]);
>  		if (err < 0)
> -			goto out_free;
> +			bus->codec_mask = 0;
>  	}
>  
>  #ifdef CONFIG_SND_HDA_PATCH_LOADER
> -- 
> 2.29.2
>