Re: [PATCH AUTOSEL 5.6 12/38] ALSA: hda: Skip controller resume if not needed

[Takashi Iwai]

On Fri, 24 Apr 2020 14:22:10 +0200,
Sasha Levin wrote:
> 
> From: Takashi Iwai <tiwai@xxxxxxx>
> 
> [ Upstream commit c4c8dd6ef807663e42a5f04ea77cd62029eb99fa ]
> 
> The HD-audio controller does system-suspend and resume operations by
> directly calling its helpers __azx_runtime_suspend() and
> __azx_runtime_resume().  However, in general, we don't have to resume
> always the device fully at the system resume; typically, if a device
> has been runtime-suspended, we can leave it to runtime resume.
> 
> Usually for achieving this, the driver would call
> pm_runtime_force_suspend() and pm_runtime_force_resume() pairs in the
> system suspend and resume ops.  Unfortunately, this doesn't work for
> the resume path in our case.  For handling the jack detection at the
> system resume, a child codec device may need the (literally) forcibly
> resume even if it's been runtime-suspended, and for that, the
> controller device must be also resumed even if it's been suspended.
> 
> This patch is an attempt to improve the situation.  It replaces the
> direct __azx_runtime_suspend()/_resume() calls with with
> pm_runtime_force_suspend() and pm_runtime_force_resume() with a slight
> trick as we've done for the codec side.  More exactly:
> 
> - azx_has_pm_runtime() check is dropped from azx_runtime_suspend() and
>   azx_runtime_resume(), so that it can be properly executed from the
>   system-suspend/resume path
> 
> - The WAKEEN handling depends on the card's power state now; it's set
>   and cleared only for the runtime-suspend
> 
> - azx_resume() checks whether any codec may need the forcible resume
>   beforehand.  If the forcible resume is required, it does temporary
>   PM refcount up/down for actually triggering the runtime resume.
> 
> - A new helper function, hda_codec_need_resume(), is introduced for
>   checking whether the codec needs a forcible runtime-resume, and the
>   existing code is rewritten with that.
> 
> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=207043
> Link: https://lore.kernel.org/r/20200413082034.25166-6-tiwai@xxxxxxx
> Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

This commit is known to cause a regression, and the fix patch is
included in today's pull request.  If we apply this, better to wait
for the next batch including its fix.


thanks,

Takashi


> ---
>  include/sound/hda_codec.h |  5 +++++
>  sound/pci/hda/hda_codec.c |  2 +-
>  sound/pci/hda/hda_intel.c | 38 +++++++++++++++++++++++++++-----------
>  3 files changed, 33 insertions(+), 12 deletions(-)
> 
> diff --git a/include/sound/hda_codec.h b/include/sound/hda_codec.h
> index 3ee8036f5436d..225154a4f2ed0 100644
> --- a/include/sound/hda_codec.h
> +++ b/include/sound/hda_codec.h
> @@ -494,6 +494,11 @@ void snd_hda_update_power_acct(struct hda_codec *codec);
>  static inline void snd_hda_set_power_save(struct hda_bus *bus, int delay) {}
>  #endif
>  
> +static inline bool hda_codec_need_resume(struct hda_codec *codec)
> +{
> +	return !codec->relaxed_resume && codec->jacktbl.used;
> +}
> +
>  #ifdef CONFIG_SND_HDA_PATCH_LOADER
>  /*
>   * patch firmware
> diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
> index 53e7732ef7520..aed1f8188e662 100644
> --- a/sound/pci/hda/hda_codec.c
> +++ b/sound/pci/hda/hda_codec.c
> @@ -2951,7 +2951,7 @@ static int hda_codec_runtime_resume(struct device *dev)
>  static int hda_codec_force_resume(struct device *dev)
>  {
>  	struct hda_codec *codec = dev_to_hda_codec(dev);
> -	bool forced_resume = !codec->relaxed_resume && codec->jacktbl.used;
> +	bool forced_resume = hda_codec_need_resume(codec);
>  	int ret;
>  
>  	/* The get/put pair below enforces the runtime resume even if the
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index aa0be85614b6c..02c6308502b1e 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -1027,7 +1027,7 @@ static int azx_suspend(struct device *dev)
>  	chip = card->private_data;
>  	bus = azx_bus(chip);
>  	snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
> -	__azx_runtime_suspend(chip);
> +	pm_runtime_force_suspend(dev);
>  	if (bus->irq >= 0) {
>  		free_irq(bus->irq, chip);
>  		bus->irq = -1;
> @@ -1044,7 +1044,9 @@ static int azx_suspend(struct device *dev)
>  static int azx_resume(struct device *dev)
>  {
>  	struct snd_card *card = dev_get_drvdata(dev);
> +	struct hda_codec *codec;
>  	struct azx *chip;
> +	bool forced_resume = false;
>  
>  	if (!azx_is_pm_ready(card))
>  		return 0;
> @@ -1055,7 +1057,20 @@ static int azx_resume(struct device *dev)
>  			chip->msi = 0;
>  	if (azx_acquire_irq(chip, 1) < 0)
>  		return -EIO;
> -	__azx_runtime_resume(chip, false);
> +
> +	/* check for the forced resume */
> +	list_for_each_codec(codec, &chip->bus) {
> +		if (hda_codec_need_resume(codec)) {
> +			forced_resume = true;
> +			break;
> +		}
> +	}
> +
> +	if (forced_resume)
> +		pm_runtime_get_noresume(dev);
> +	pm_runtime_force_resume(dev);
> +	if (forced_resume)
> +		pm_runtime_put(dev);
>  	snd_power_change_state(card, SNDRV_CTL_POWER_D0);
>  
>  	trace_azx_resume(chip);
> @@ -1102,12 +1117,12 @@ static int azx_runtime_suspend(struct device *dev)
>  	if (!azx_is_pm_ready(card))
>  		return 0;
>  	chip = card->private_data;
> -	if (!azx_has_pm_runtime(chip))
> -		return 0;
>  
>  	/* enable controller wake up event */
> -	azx_writew(chip, WAKEEN, azx_readw(chip, WAKEEN) |
> -		  STATESTS_INT_MASK);
> +	if (snd_power_get_state(card) == SNDRV_CTL_POWER_D0) {
> +		azx_writew(chip, WAKEEN, azx_readw(chip, WAKEEN) |
> +			   STATESTS_INT_MASK);
> +	}
>  
>  	__azx_runtime_suspend(chip);
>  	trace_azx_runtime_suspend(chip);
> @@ -1118,17 +1133,18 @@ static int azx_runtime_resume(struct device *dev)
>  {
>  	struct snd_card *card = dev_get_drvdata(dev);
>  	struct azx *chip;
> +	bool from_rt = snd_power_get_state(card) == SNDRV_CTL_POWER_D0;
>  
>  	if (!azx_is_pm_ready(card))
>  		return 0;
>  	chip = card->private_data;
> -	if (!azx_has_pm_runtime(chip))
> -		return 0;
> -	__azx_runtime_resume(chip, true);
> +	__azx_runtime_resume(chip, from_rt);
>  
>  	/* disable controller Wake Up event*/
> -	azx_writew(chip, WAKEEN, azx_readw(chip, WAKEEN) &
> -			~STATESTS_INT_MASK);
> +	if (from_rt) {
> +		azx_writew(chip, WAKEEN, azx_readw(chip, WAKEEN) &
> +			   ~STATESTS_INT_MASK);
> +	}
>  
>  	trace_azx_runtime_resume(chip);
>  	return 0;
> -- 
> 2.20.1
>