Re: [PATCH V6 11/21] clk: tegra: clk-dfll: Add suspend and resume support

[Sowjanya Komatineni]

On 7/21/19 2:32 PM, Dmitry Osipenko wrote:
> 21.07.2019 22:40, Sowjanya Komatineni ÐÐÑÐÑ:
> > This patch implements DFLL suspend and resume operation.
> >
> > During system suspend entry, CPU clock will switch CPU to safe
> > clock source of PLLP and disables DFLL clock output.
> >
> > DFLL driver suspend confirms DFLL disable state and errors out on
> > being active.
> >
> > DFLL is re-initialized during the DFLL driver resume as it goes
> > through complete reset during suspend entry.
> >
> > Acked-by: Thierry Reding <treding@xxxxxxxxxx>
> > Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
> > ---
> >   drivers/clk/tegra/clk-dfll.c               | 44 ++++++++++++++++++++++++++++++
> >   drivers/clk/tegra/clk-dfll.h               |  2 ++
> >   drivers/clk/tegra/clk-tegra124-dfll-fcpu.c |  1 +
> >   3 files changed, 47 insertions(+)
> >
> > diff --git a/drivers/clk/tegra/clk-dfll.c b/drivers/clk/tegra/clk-dfll.c
> > index f8688c2ddf1a..7dcad4ccd0ae 100644
> > --- a/drivers/clk/tegra/clk-dfll.c
> > +++ b/drivers/clk/tegra/clk-dfll.c
> > @@ -1513,6 +1513,50 @@ static int dfll_init(struct tegra_dfll *td)
> >   	return ret;
> >   }
> >   
> > +/**
> > + * tegra_dfll_suspend - check DFLL is disabled
> > + * @dev: DFLL device *
> > + *
> > + * DFLL clock should be disabled by the CPUFreq driver. So, make
> > + * sure it is disabled and disable all clocks needed by the DFLL.
> > + */
> > +int tegra_dfll_suspend(struct device *dev)
> > +{
> > +	struct tegra_dfll *td = dev_get_drvdata(dev);
> > +
> > +	if (dfll_is_running(td)) {
> > +		dev_warn(td->dev, "failed disabling the dfll\n");
> Something like "dfll is enabled while shouldn't be\n" will be more
> informative.
>
> This is a error, hence dev_err().
>
> > +		return -EBUSY;
> > +	}
> > +
> > +	pm_runtime_disable(dev);
> > +
> > +	clk_unprepare(td->ref_clk);
> > +	clk_unprepare(td->soc_clk);
> > +	clk_unprepare(td->i2c_clk);
> Please don't do this, DFLL is already disabled if not running.

during resume dfll re-init sequence is same as dfll init so I am using 
existing dfll_init

which includes runtime_enable and clk_prepare.


Will create separate dfll_reinit then...

> > +	reset_control_assert(td->dvco_rst);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL(tegra_dfll_suspend);
> > +
> > +/**
> > + * tegra_dfll_resume - reinitialize DFLL on resume
> > + * @pdev: DFLL instance
> > + *
> > + * Re-initialize DFLL on resume as it gets disabled and reset during
> > + * suspend entry. DFLL clock is enabled in closed loop mode later
> > + * and CPU frequency will be switched to DFLL output.
> > + */
> > +int tegra_dfll_resume(struct device *dev)
> > +{
> > +	struct tegra_dfll *td = dev_get_drvdata(dev);
> > +
> > +	return dfll_init(td);
> Just create dfll_reinit() variant.
>
> > +}
> > +EXPORT_SYMBOL(tegra_dfll_resume);
> > +
> >   /*
> >    * DT data fetch
> >    */
> > diff --git a/drivers/clk/tegra/clk-dfll.h b/drivers/clk/tegra/clk-dfll.h
> > index 1b14ebe7268b..fb209eb5f365 100644
> > --- a/drivers/clk/tegra/clk-dfll.h
> > +++ b/drivers/clk/tegra/clk-dfll.h
> > @@ -42,5 +42,7 @@ int tegra_dfll_register(struct platform_device *pdev,
> >   struct tegra_dfll_soc_data *tegra_dfll_unregister(struct platform_device *pdev);
> >   int tegra_dfll_runtime_suspend(struct device *dev);
> >   int tegra_dfll_runtime_resume(struct device *dev);
> > +int tegra_dfll_suspend(struct device *dev);
> > +int tegra_dfll_resume(struct device *dev);
> >   
> >   #endif /* __DRIVERS_CLK_TEGRA_CLK_DFLL_H */
> > diff --git a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
> > index e84b6d52cbbd..2ac2679d696d 100644
> > --- a/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
> > +++ b/drivers/clk/tegra/clk-tegra124-dfll-fcpu.c
> > @@ -631,6 +631,7 @@ static int tegra124_dfll_fcpu_remove(struct platform_device *pdev)
> >   static const struct dev_pm_ops tegra124_dfll_pm_ops = {
> >   	SET_RUNTIME_PM_OPS(tegra_dfll_runtime_suspend,
> >   			   tegra_dfll_runtime_resume, NULL)
> > +	SET_SYSTEM_SLEEP_PM_OPS(tegra_dfll_suspend, tegra_dfll_resume)
> >   };
> >   
> >   static struct platform_driver tegra124_dfll_fcpu_driver = {