Re: [PATCH V2] i2c: busses: tegra: Add suspend-resume support

[Bitan Biswas]

On 6/6/19 5:06 AM, Dmitry Osipenko wrote:
> 06.06.2019 8:54, Bitan Biswas ÐÐÑÐÑ:
> > Post suspend I2C registers have power on reset values. Before any
> > transfer initialize I2C registers to prevent I2C transfer timeout
> > and implement suspend and resume callbacks needed. Fix below errors
> > post suspend:
> >
> > 1) Tegra I2C transfer timeout during jetson tx2 resume:
> >
> > [   27.520613] pca953x 1-0074: calling pca953x_resume+0x0/0x1b0 @ 2939, parent: i2c-1
> > [   27.633623] tegra-i2c 3160000.i2c: i2c transfer timed out
> > [   27.639162] pca953x 1-0074: Unable to sync registers 0x3-0x5. -110
> > [   27.645336] pca953x 1-0074: Failed to sync GPIO dir registers: -110
> > [   27.651596] PM: dpm_run_callback(): pca953x_resume+0x0/0x1b0 returns -110
> > [   27.658375] pca953x 1-0074: pca953x_resume+0x0/0x1b0 returned -110 after 127152 usecs
> > [   27.666194] PM: Device 1-0074 failed to resume: error -110
> >
> > 2) Tegra I2C transfer timeout error on jetson Xavier post resume.
> >
> > Remove i2c bus lock-unlock calls in resume callback as i2c_mark_adapter_*
> > (suspended-resumed) help ensure i2c core calls from client are not
> > executed before i2c-tegra resume.
> >
> > Signed-off-by: Bitan Biswas <bbiswas@xxxxxxxxxx>
> > ---
> >   drivers/i2c/busses/i2c-tegra.c | 23 +++++++++++++++++++++++
> >   1 file changed, 23 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> > index ebaa78d..76b7926 100644
> > --- a/drivers/i2c/busses/i2c-tegra.c
> > +++ b/drivers/i2c/busses/i2c-tegra.c
> > @@ -1687,7 +1687,30 @@ static int tegra_i2c_remove(struct platform_device *pdev)
> >   }
> >   
> >   #ifdef CONFIG_PM_SLEEP
> > +static int tegra_i2c_suspend(struct device *dev)
> > +{
> > +	struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);
> > +
> > +	i2c_mark_adapter_suspended(&i2c_dev->adapter);
> > +
> > +	return 0;
> > +}
> > +
> > +static int tegra_i2c_resume(struct device *dev)
> > +{
> > +	struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	ret = tegra_i2c_init(i2c_dev, false);
> > +	if (ret)
> > +		return ret;
>
> We're expecting that tegra_i2c_init returns a error code on a failure
> and nothing else, hence it will be a bit more expressive to name the
> returned variable as "err". There is nothing wrong with yours variant,
> this is just a very minor recommendation from me. Please note that a bit
> more wise choice of the names makes easier to follow the code for other
> people and hence results in a cleaner code.
Agreed.

> > +
> > +	i2c_mark_adapter_resumed(&i2c_dev->adapter);
>
> Please add a blank line here for a better readability and to make the
> patch consistent. You added the blank line in a similar case of
> tegra_i2c_suspend() and this makes it inconsistent.
OK.

> > +	return 0;
> > +}
> > +
> >   static const struct dev_pm_ops tegra_i2c_pm = {
> > +	SET_SYSTEM_SLEEP_PM_OPS(tegra_i2c_suspend, tegra_i2c_resume)
> >   	SET_RUNTIME_PM_OPS(tegra_i2c_runtime_suspend, tegra_i2c_runtime_resume,
> >   			   NULL)
> >   };
I shall send updated patch with suggested changes.

-thanks,
 Bitan