linux-kernel - Re: [PATCH] ASoC: tas27{64,70}: fix PM ops ordering

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Message-Id: <642B09FF-E7CC-481A-9EC7-88B74FA830CB@cutebit.org>
Date:   Fri, 2 Dec 2022 13:24:38 +0100
From:   Martin Povišer <povik+lin@...ebit.org>
To:     James Calligeros <jcalligeros99@...il.com>
Cc:     Linux-ALSA <alsa-devel@...a-project.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        shenghao-ding@...com, kevin-lu@...com
Subject: Re: [PATCH] ASoC: tas27{64,70}: fix PM ops ordering

(Copying in some TI addresses which may be interested.)

> On 2. 12. 2022, at 12:58, James Calligeros <jcalligeros99@...il.com> wrote:
> 
> On both tas2764 and tas2770, a write to PWR_CTRL is attempted
> on resume before syncing the regcache to the chip, potentially leaving
> it in an undefined state that causes resume to fail. The codec
> is then unavailable until the next system reset.

I think we need to split this into separate tas2764 and tas2770 changes.
So, concentrating on tas2764 first:

The issue here isn’t that a write is attempted before the device is synced
and while the regcache is in cache-only state. That’s on its own OK.
The issue here is that all registers including PWR_CTRL are restored in
one go, and that can cause issues since we need the device properly
configured before raising its power state.

> On tas2770 specifically, both suspend and resume ops attempt useless
> register writes on unrestored registers. This causes its state to be
> desynchronised from what ASoC expects it to be in.
> 
> These two codecs are almost identical, so unify their behaviour
> and reorder the ops so that the codec is always suspended and
> resumed in a known/expected state.

I suggest we make the first commit fix up tas2764 suspend/resume
code to a state that’s OK, then second commit copies that over
to tas2770 to replace what’s there now. (Pointing out some of the
things that’s wrong with the old code.)

> Suggested-by: Martin Povišer <povik+lin@...ebit.org>
> Signed-off-by: James Calligeros <jcalligeros99@...il.com>
> ---
> sound/soc/codecs/tas2764.c | 11 +++++++----
> sound/soc/codecs/tas2770.c | 40 ++++++++++++++++++++------------------
> 2 files changed, 28 insertions(+), 23 deletions(-)
> 
> diff --git a/sound/soc/codecs/tas2764.c b/sound/soc/codecs/tas2764.c
> index 2e0ed3e68fa5..51c6b3a940c4 100644
> --- a/sound/soc/codecs/tas2764.c
> +++ b/sound/soc/codecs/tas2764.c
> @@ -32,7 +32,7 @@ struct tas2764_priv {
> 	struct regmap *regmap;
> 	struct device *dev;
> 	int irq;
> -	
> +

Stray whiteline change here

> 	int v_sense_slot;
> 	int i_sense_slot;
> 
> @@ -157,14 +157,17 @@ static int tas2764_codec_resume(struct snd_soc_component *component)
> 		usleep_range(1000, 2000);
> 	}
> 
> -	ret = tas2764_update_pwr_ctrl(tas2764);
> +	regcache_cache_only(tas2764->regmap, false);
> 
> +	ret = regcache_sync(tas2764->regmap);
> 	if (ret < 0)
> 		return ret;
> 
> -	regcache_cache_only(tas2764->regmap, false);
> +	ret = tas2764_update_pwr_ctrl(tas2764);
> +	if (ret < 0)
> +		return ret;
> 
> -	return regcache_sync(tas2764->regmap);
> +	return 0;
> }
> #else
> #define tas2764_codec_suspend NULL
> diff --git a/sound/soc/codecs/tas2770.c b/sound/soc/codecs/tas2770.c
> index 8557759acb1f..5c9e8419b387 100644
> --- a/sound/soc/codecs/tas2770.c
> +++ b/sound/soc/codecs/tas2770.c
> @@ -72,25 +72,21 @@ static int tas2770_codec_suspend(struct snd_soc_component *component)
> 	struct tas2770_priv *tas2770 = snd_soc_component_get_drvdata(component);
> 	int ret = 0;
> 
> +	ret = snd_soc_component_update_bits(component, TAS2770_PWR_CTRL,
> +						TAS2770_PWR_CTRL_MASK,
> +						TAS2770_PWR_CTRL_SHUTDOWN);
> +
> +	if (ret < 0)
> +		return ret;
> +
> 	regcache_cache_only(tas2770->regmap, true);
> -	regcache_mark_dirty(tas2770->regmap);
> +	regcache_sync(tas2770->regmap);
> 
> -	if (tas2770->sdz_gpio) {
> +	if (tas2770->sdz_gpio)
> 		gpiod_set_value_cansleep(tas2770->sdz_gpio, 0);
> -	} else {
> -		ret = snd_soc_component_update_bits(component, TAS2770_PWR_CTRL,
> -						    TAS2770_PWR_CTRL_MASK,
> -						    TAS2770_PWR_CTRL_SHUTDOWN);
> -		if (ret < 0) {
> -			regcache_cache_only(tas2770->regmap, false);
> -			regcache_sync(tas2770->regmap);
> -			return ret;
> -		}
> 
> -		ret = 0;
> -	}
> 
> -	return ret;
> +	return 0;
> }
> 
> static int tas2770_codec_resume(struct snd_soc_component *component)
> @@ -98,18 +94,24 @@ static int tas2770_codec_resume(struct snd_soc_component *component)
> 	struct tas2770_priv *tas2770 = snd_soc_component_get_drvdata(component);
> 	int ret;
> 
> +
> 	if (tas2770->sdz_gpio) {
> 		gpiod_set_value_cansleep(tas2770->sdz_gpio, 1);
> 		usleep_range(1000, 2000);
> -	} else {
> -		ret = tas2770_update_pwr_ctrl(tas2770);
> -		if (ret < 0)
> -			return ret;
> 	}
> 
> 	regcache_cache_only(tas2770->regmap, false);
> 
> -	return regcache_sync(tas2770->regmap);
> +	ret = regcache_sync(tas2770->regmap);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = tas2770_update_pwr_ctrl(tas2770);
> +	if (ret < 0)
> +		return ret;
> +
> +
> +	return 0;
> }
> #else
> #define tas2770_codec_suspend NULL
> -- 
> 2.38.1
>