Re: [PATCH] ASoC: ak4642: Enable cache usage to fix crashes on resume

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

On 05/18/16 20:49, Mark Brown wrote:
> The ak4642 driver is using a regmap cache sync to restore the
> configuration of the chip on resume but (as Peter observed) does not
> actually define a register cache which means that the resume is never
> going to work and we trigger asserts in regmap.  Fix this by enabling
> caching.

Should the ak4642 implement the suspend callback and:

static int ak4642_suspend(struct snd_soc_codec *codec)
{
	struct regmap *regmap = dev_get_regmap(codec->dev, NULL);

	regcache_cache_only(regmap, true);
	regcache_mark_dirty(regmap);
	return 0;
}

static int ak4642_resume(struct snd_soc_codec *codec)
{
	struct regmap *regmap = dev_get_regmap(codec->dev, NULL);

	regcache_cache_only(regmap, false);
	regcache_sync(regmap);
	return 0;
}

I know it is highly unlikely that anything is going to be written to the chip
while the board is suspended. Probably the suspend and changing the cache only
is not needed, but in this way things look a bit more complete?

> 
> Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
> Reported-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> Cc: stable@vger.kernel.org
> ---
>  sound/soc/codecs/ak4642.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/sound/soc/codecs/ak4642.c b/sound/soc/codecs/ak4642.c
> index 1ee8506c06c7..4d8b9e49e8d6 100644
> --- a/sound/soc/codecs/ak4642.c
> +++ b/sound/soc/codecs/ak4642.c
> @@ -560,6 +560,7 @@ static const struct regmap_config ak4642_regmap = {
>  	.max_register		= FIL1_3,
>  	.reg_defaults		= ak4642_reg,
>  	.num_reg_defaults	= NUM_AK4642_REG_DEFAULTS,
> +	.cache_type		= REGCACHE_RBTREE,
>  };
>  
>  static const struct regmap_config ak4643_regmap = {
> @@ -568,6 +569,7 @@ static const struct regmap_config ak4643_regmap = {
>  	.max_register		= SPK_MS,
>  	.reg_defaults		= ak4643_reg,
>  	.num_reg_defaults	= ARRAY_SIZE(ak4643_reg),
> +	.cache_type		= REGCACHE_RBTREE,
>  };
>  
>  static const struct regmap_config ak4648_regmap = {
> @@ -576,6 +578,7 @@ static const struct regmap_config ak4648_regmap = {
>  	.max_register		= EQ_FBEQE,
>  	.reg_defaults		= ak4648_reg,
>  	.num_reg_defaults	= ARRAY_SIZE(ak4648_reg),
> +	.cache_type		= REGCACHE_RBTREE,
>  };
>  
>  static const struct ak4642_drvdata ak4642_drvdata = {
> 


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