Re: [RFC PATCH v4 04/14] i2c: tegra: Fix runtime resume to re-init VI I2C

[Sowjanya Komatineni]

On 7/26/20 4:53 PM, Dmitry Osipenko wrote:
> 24.07.2020 02:51, Sowjanya Komatineni ÐÐÑÐÑ:
> > VI I2C is on host1x bus and is part of VE power domain.
> >
> > During suspend/resume VE power domain goes through power off/on.
> >
> > So, controller reset followed by i2c re-initialization is required
> > after the domain power up.
> >
> > This patch fixes it.
> >
> > Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> > ---
> >   drivers/i2c/busses/i2c-tegra.c | 16 ++++++++++++++++
> >   1 file changed, 16 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> > index 7b93c45..1bf3666 100644
> > --- a/drivers/i2c/busses/i2c-tegra.c
> > +++ b/drivers/i2c/busses/i2c-tegra.c
> > @@ -293,6 +293,8 @@ struct tegra_i2c_dev {
> >   	bool is_curr_atomic_xfer;
> >   };
> >   
> > +static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev, bool clk_reinit);
> > +
> >   static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val,
> >   		       unsigned long reg)
> >   {
> > @@ -675,8 +677,22 @@ static int __maybe_unused tegra_i2c_runtime_resume(struct device *dev)
> >   		goto disable_slow_clk;
> >   	}
> >   
> > +	/*
> > +	 * VI I2C device is attached to VE power domain which goes through
> > +	 * power ON/OFF during PM runtime resume/suspend. So, controller
> > +	 * should go through reset and need to re-initialize after power
> > +	 * domain ON.
> > +	 */
> > +	if (i2c_dev->is_vi) {
> > +		ret = tegra_i2c_init(i2c_dev, true);
> > +		if (ret)
> > +			goto disable_div_clk;
> > +	}
> > +
> >   	return 0;
> >   
> > +disable_div_clk:
> > +	clk_disable(i2c_dev->div_clk);
> >   disable_slow_clk:
> >   	clk_disable(i2c_dev->slow_clk);
> >   disable_fast_clk:
> This look okay, but isn't RPM usage a bit too expensive for VI? Maybe
> RPM autodelay needs to be set for the I2C driver?
>
> Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Thanks Dmitry. Will look into and have separate patch for VI I2C RPM 
auto-delay out of this series sometime next week.

Regards

Sowjanya