linux-kernel - Re: [PATCH v3 06/19] ASoC: sun4i-i2s: Fix sun8i volatile regs

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Message-ID: <CAJiuCccEVOcD38DZLru2PirGhRBaeJqFAug_aZjW+QY0xHTb1g@mail.gmail.com>
Date:   Sun, 20 Sep 2020 22:05:48 +0200
From:   Clément Péron <peron.clem@...il.com>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Maxime Ripard <mripard@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Marcus Cooper <codekipper@...il.com>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Linux-ALSA <alsa-devel@...a-project.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-sunxi <linux-sunxi@...glegroups.com>
Subject: Re: [PATCH v3 06/19] ASoC: sun4i-i2s: Fix sun8i volatile regs

Hi Samuel,

On Sun, 20 Sep 2020 at 20:52, Samuel Holland <samuel@...lland.org> wrote:
>
> On 9/20/20 1:07 PM, Clément Péron wrote:
> > The FIFO TX reg is volatile and sun8i i2s register
> > mapping is different from sun4i.
> >
> > Even if in this case it's doesn't create an issue,
> > Avoid setting some regs that are undefined in sun8i.
> >
> > Signed-off-by: Clément Péron <peron.clem@...il.com>
> > Acked-by: Maxime Ripard <mripard@...nel.org>
> > ---
> >  sound/soc/sunxi/sun4i-i2s.c | 15 +++++++++++----
> >  1 file changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
> > index ce4913f0ffe4..a35be0e2baf5 100644
> > --- a/sound/soc/sunxi/sun4i-i2s.c
> > +++ b/sound/soc/sunxi/sun4i-i2s.c
> > @@ -1126,12 +1126,19 @@ static bool sun8i_i2s_rd_reg(struct device *dev, unsigned int reg)
> >
> >  static bool sun8i_i2s_volatile_reg(struct device *dev, unsigned int reg)
> >  {
> > -     if (reg == SUN8I_I2S_INT_STA_REG)
> > +     switch (reg) {
> > +     case SUN4I_I2S_FIFO_CTRL_REG:
>
> Please check if this breaks audio recording with runtime PM enabled. I noticed
> this with an older revision of the series that also changed
> sun4i_i2s_volatile_reg. Marking SUN4I_I2S_FIFO_CTRL_REG as volatile broke
> setting of SUN4I_I2S_FIFO_CTRL_TX_MODE/RX_MODE, because the set_fmt() callback
> is not run with a runtime PM reference held, and volatile registers are not
> written by regcache_sync() during sun4i_i2s_runtime_resume().
>
> As a workaround, I moved the TX_MODE/RX_MODE initialization to hw_params(), but
> I am not sure it is the right thing to do:

Thanks for the catch,
I never tried to suspend/resume my board actually.
But your explanation and the fix seems legit to me.

I don't think it's a workaround as settings the fifo size is not
related to set_fmt and could also be set in hw_params.

I will add your fix in the next version.

Regards,
Clement

>
> https://github.com/smaeul/linux/commit/5e40ac610986.patch
>
> Cheers,
> Samuel
>
> > +     case SUN4I_I2S_FIFO_RX_REG:
> > +     case SUN4I_I2S_FIFO_STA_REG:
> > +     case SUN4I_I2S_RX_CNT_REG:
> > +     case SUN4I_I2S_TX_CNT_REG:
> > +     case SUN8I_I2S_FIFO_TX_REG:
> > +     case SUN8I_I2S_INT_STA_REG:
> >               return true;
> > -     if (reg == SUN8I_I2S_FIFO_TX_REG)
> > -             return false;
> >
> > -     return sun4i_i2s_volatile_reg(dev, reg);
> > +     default:
> > +             return false;
> > +     }
> >  }
> >
> >  static const struct reg_default sun4i_i2s_reg_defaults[] = {
> >
>