Re: [PATCH 03/16] ASoC: tas2781: disable regmap regcache

Gergo Koteles
2023-12-07T20:19:43Z

On Thu, 2023-12-07 at 18:20 +0000, Mark Brown wrote:
> On Thu, Dec 07, 2023 at 12:59:44AM +0100, Gergo Koteles wrote:
>
> > The amp has 3 level addressing (BOOK, PAGE, REG).
> > The regcache couldn't handle it.
>
> So the books aren't currently used so the driver actually works?
>
It writes to the book 0 and 8c. The initialization works with regcache,
because it writes also the i2c devices.

> > static int tas2781_system_suspend(struct device *dev)
> > @@ -770,10 +758,7 @@ static int tas2781_system_suspend(struct device *dev)
> > return ret;
> >
> > /* Shutdown chip before system suspend */
> > - regcache_cache_only(tas_priv->regmap, false);
> > tasdevice_tuning_switch(tas_priv, 1);
> > - regcache_cache_only(tas_priv->regmap, true);
> > - regcache_mark_dirty(tas_priv->regmap);
> >
> > /*
> > * Reset GPIO may be shared, so cannot reset here.
>
> How can this work over system suspend? This just removes the cache with
> no replacement so if the device looses power over suspend (which seems
> likely) then all the register state will be lost. A similar issue may
> potentially exist over runtime suspend on an ACPI system with
> sufficiently heavily optimised power management.

In runtime_resume, only one of the two amplifiers goes back.
The runtime_suspend sets the current book/prog/conf to -1 on all
devices, and tas2781_hda_playback_hook will restore the
program/configuration/profile with tasdevice_tuning_switch.

And only one, because tasdevice_change_chn_book directly changes the
address of i2c_client, so the unlucky one gets invalid values in its
actual book from regcache_sync.

system_restore doesn't work at all, because regcache_cache_only stays
true since system_suspend.

It works without the regcache functions.