linux-kernel - Re: [PATCH] ASoC: pcm512x: Mend accesses to the I2S_1 and I2S

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Date:   Tue, 21 Sep 2021 15:30:31 +0200
From:   Peter Rosin <peda@...ntia.se>
To:     Mark Brown <broonie@...nel.org>
Cc:     Péter Ujfalusi <peter.ujfalusi@...il.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Kirill Marinushkin <kmarinushkin@...dec.com>
Subject: Re: [PATCH] ASoC: pcm512x: Mend accesses to the I2S_1 and I2S_2
 registers

On 2021-09-21 14:01, Mark Brown wrote:
> On Tue, Sep 21, 2021 at 10:48:01AM +0200, Peter Rosin wrote:
>> On 2021-09-21 10:10, Peter Rosin wrote:
> 
>> Ok, so the attached works for me as well. But I don't know if it's
>> appropriate to resume/suspend like that?
> 
>> is:
>>
>> pcm512x 0-004c: Failed to set data format: -16
>>
>> The root cause is that the chip is in Powerdown mode when
>> pcm512x_set_fmt runs. So, bring the chip out of suspend for
>> the update of the format.
> 
> How would this work if the device looses power while in suspend (eg, due
> to the regulators being software controllable)?  If the data isn't being
> stored in the cache then it'll need to be stored somewhere else and
> restored on resume.

Right. Scratch v2. I'd go with the original patch. We have verified
that the original content of the I2S_1 register is the expected 0x02
(at least on one pcm5142) and besides, the four RSV bits are probably
don't care anyway.

Péter might have a different opinion?

Cheers,
Peter