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

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Date:   Thu, 7 Dec 2023 22:39:16 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Gergo Koteles <soyer@....hu>
Cc:     Shenghao Ding <shenghao-ding@...com>, Kevin Lu <kevin-lu@...com>,
        Baojun Xu <baojun.xu@...com>, Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH 03/16] ASoC: tas2781: disable regmap regcache

On Thu, Dec 07, 2023 at 10:12:13PM +0100, Gergo Koteles wrote:
> On Thu, 2023-12-07 at 20:36 +0000, Mark Brown wrote:

> > > 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.

> > The code creates the impression that writing to one tas2781 writes to
> > all of them, is that not the case?

> Yes, the tasdevice_* functions, but the regcache_sync doesn't know
> this.

So this syncing is done in software not hardware?  My understanding was
that this was a hardware thing.

> > How would the devices get their configuration restored?

> tasdevice_tuning_switch calls tasdevice_select_tuningprm_cfg which
> checks whether the devices needs a new program or configuration.

> the runtime_suspend and system resume set the devices cur_prog,
> cur_conf to -1.

...

> The tas2781_hda_playback_hook calls the tasdevice_tuning_switch

And there are no registers other than these programs?

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