linux-kernel - Re: [PATCH] ASoC: wm8962: restore the CLOCKING2 register in resume

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Date:   Thu, 23 Apr 2020 07:38:04 +0000
From:   "S.j. Wang" <shengjiu.wang@....com>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>
CC:     "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "perex@...ex.cz" <perex@...ex.cz>,
        "tiwai@...e.com" <tiwai@...e.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "allison@...utok.net" <allison@...utok.net>,
        "info@...ux.net" <info@...ux.net>,
        "patches@...nsource.cirrus.com" <patches@...nsource.cirrus.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: wm8962: restore the CLOCKING2 register in resume


> 
> On Tue, Apr 21, 2020 at 08:02:15PM +0800, Shengjiu Wang wrote:
> > The CLOCKING2 is a volatile register, but some bits should be restored
> > when resume, for example SYSCLK_SRC. otherwise the output clock is
> > wrong
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>
> > ---
> >  sound/soc/codecs/wm8962.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/sound/soc/codecs/wm8962.c b/sound/soc/codecs/wm8962.c
> > index d9d59f45833f..6e96c0c5ad2a 100644
> > --- a/sound/soc/codecs/wm8962.c
> > +++ b/sound/soc/codecs/wm8962.c
> > @@ -82,6 +82,7 @@ struct wm8962_priv {  #endif
> >
> >       int irq;
> > +     u32 regcache_clocking2;
> >  };
> >
> >  /* We can't use the same notifier block for more than one supply and
> > @@ -3813,6 +3814,10 @@ static int wm8962_runtime_resume(struct
> device
> > *dev)
> >
> >       regcache_sync(wm8962->regmap);
> >
> > +     regmap_update_bits(wm8962->regmap, WM8962_CLOCKING2,
> > +                        WM8962_SYSCLK_SRC_MASK,
> > +                        wm8962->regcache_clocking2);
> > +
> 
> I wonder if it might just be better to make the register non-volatile? From
> looking through the datasheet I am guessing this is volatile for the
> CLASSD_CLK_DIV bits, which are controlled by the chip itself. But the
> datasheet claims these are read only and protected by the security key, and
> they are not read by the driver at all.
> 
> Thanks,
> Charles
> 
Use non-volatile also can fix the issue, I will send v2 for it

Best regards
Wang shengjiu