linux-kernel - Re: [alsa-devel] [PATCH] ASoC: sgtl5000: only check VDDD-supply, not revision

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Date:	Mon, 6 Jun 2016 18:45:47 +0200
From:	Clemens Gruber <clemens.gruber@...ruber.com>
To:	Fabio Estevam <festevam@...il.com>
Cc:	Eric Nelson <eric@...int.com>, Mark Brown <broonie@...nel.org>,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [alsa-devel] [PATCH] ASoC: sgtl5000: only check VDDD-supply, not
 revision

Hi Fabio,

On Sun, Jun 05, 2016 at 10:22:55PM -0300, Fabio Estevam wrote:
> Hi Clemens,
> 
> On Sun, Jun 5, 2016 at 8:16 PM, Clemens Gruber
> <clemens.gruber@...ruber.com> wrote:
> 
> > I looked into this today and discovered the following:
> >
> > With my patch applied, if I reset the board just after playback, at the
> > next boot, the sgtl5000_fill_defaults function does not succeed: Writing
> > the default value 0x7060 to register 0x30 (CHIP_ANA_POWER) fails.
> >
> > How did CHIP_ANA_POWER change with my patch: Before, only
> > LINREG_SIMPLE_POWERUP was cleared as is recommended in the datasheet
> > when using the internal LDO, now both LINREG_SIMPLE_POWERUP and
> > STARTUP_POWERUP are cleared, as is recommended when using external VDDD.
> >
> > But why does the SGTL5000 nack that default write to CHIP_ANA_POWER
> > after a reboot, which interrupted the playback?
> >
> > The following patch from Eric solved the problem; one write fails but it
> > continues setting the other registers and thus even if resetting a board
> > during playback, the sound still works after reboot:
> > http://mailman.alsa-project.org/pipermail/alsa-devel/2015-February/088356.html
> > Another workaround might be to not even write a default value to
> > CHIP_ANA_POWER, as in this patch from Eric:
> > http://mailman.alsa-project.org/pipermail/alsa-devel/2015-February/088355.html
> >
> > What do you think we should do?
> 
> Shouldn't both patches be applied?

Yes, I think so too. However I am unsure if we should also remove
SGTL5000_CHIP_LINREG_CTRL from the defaults as in Eric's patch 3/6 or
only keep the parts of the patch dealing with SGTL5000_CHIP_ANA_POWER.
What do you think?

Regards,
Clemens