linux-kernel - Re: [PATCH AUTOSEL 4.9 03/13] ALSA: hda: Keep the controller initialization even if no codecs found

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Date:   Fri, 24 Apr 2020 14:45:55 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Roy Spliet <nouveau@...iet.org>, alsa-devel@...a-project.org
Subject: Re: [PATCH AUTOSEL 4.9 03/13] ALSA: hda: Keep the controller initialization even if no codecs found

On Fri, 24 Apr 2020 14:24:36 +0200,
Sasha Levin wrote:
> 
> From: Takashi Iwai <tiwai@...e.de>
> 
> [ Upstream commit 9479e75fca370a5220784f7596bf598c4dad0b9b ]
> 
> Currently, when the HD-audio controller driver doesn't detect any
> codecs, it tries to abort the probe.  But this abort happens at the
> delayed probe, i.e. the primary probe call already returned success,
> hence the driver is never unbound until user does so explicitly.
> As a result, it may leave the HD-audio device in the running state
> without the runtime PM.  More badly, if the device is a HD-audio bus
> that is tied with a GPU, GPU cannot reach to the full power down and
> consumes unnecessarily much power.
> 
> This patch changes the logic after no-codec situation; it continues
> probing without the further codec initialization but keep the
> controller driver running normally.
> 
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207043
> Tested-by: Roy Spliet <nouveau@...iet.org>
> Link: https://lore.kernel.org/r/20200413082034.25166-5-tiwai@suse.de
> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> Signed-off-by: Sasha Levin <sashal@...nel.org>

Applying this without other commits isn't recommended, especially for
the older branches.  Maybe OK up from 4.19, but I'd avoid applying for
the older.


thanks,

Takashi



> ---
>  sound/pci/hda/hda_intel.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 5a578ebca1055..8b9d1c6574e43 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -1806,7 +1806,7 @@ static int azx_first_init(struct azx *chip)
>  	/* codec detection */
>  	if (!azx_bus(chip)->codec_mask) {
>  		dev_err(card->dev, "no codecs found!\n");
> -		return -ENODEV;
> +		/* keep running the rest for the runtime PM */
>  	}
>  
>  	if (azx_acquire_irq(chip, 0) < 0)
> @@ -2129,9 +2129,11 @@ static int azx_probe_continue(struct azx *chip)
>  #endif
>  
>  	/* create codec instances */
> -	err = azx_probe_codecs(chip, azx_max_codecs[chip->driver_type]);
> -	if (err < 0)
> -		goto out_free;
> +	if (bus->codec_mask) {
> +		err = azx_probe_codecs(chip, azx_max_codecs[chip->driver_type]);
> +		if (err < 0)
> +			goto out_free;
> +	}
>  
>  #ifdef CONFIG_SND_HDA_PATCH_LOADER
>  	if (chip->fw) {
> @@ -2145,7 +2147,7 @@ static int azx_probe_continue(struct azx *chip)
>  #endif
>  	}
>  #endif
> -	if ((probe_only[dev] & 1) == 0) {
> +	if (bus->codec_mask && !(probe_only[dev] & 1)) {
>  		err = azx_codec_configure(chip);
>  		if (err < 0)
>  			goto out_free;
> -- 
> 2.20.1
>