13.12.2019 02:34, Dmitry Osipenko пишет:
> I noticed that sometime I2C clock is kept enabled during suspend-resume.
> This happens because runtime PM defers dynamic suspension and thus it may
> happen that runtime PM is in active state when system enters into suspend.
> In particular I2C controller that is used for CPU's DVFS is often kept ON
> during suspend because CPU's voltage scaling happens quite often.
>
> Note: we marked runtime PM as IRQ-safe during the driver's probe in the
> "Support atomic transfers" patch, thus it's okay to enforce runtime PM
> suspend/resume in the NOIRQ phase which is used for the system-level
> suspend/resume of the driver.
>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-tegra.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index b3ecdd87e91f..d309a314f4d6 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -1790,9 +1790,14 @@ static int tegra_i2c_remove(struct platform_device *pdev)
> static int __maybe_unused tegra_i2c_suspend(struct device *dev)
> {
> struct tegra_i2c_dev *i2c_dev = dev_get_drvdata(dev);
> + int err;
>
> i2c_mark_adapter_suspended(&i2c_dev->adapter);
I'm now in a doubt that it is correct to use NOIRQ level at all for the
suspend because i2c_mark_adapter_suspended() uses mutex, thus I'm
wondering what will happen if there is an asynchronous transfer
happening during suspend..
The i2c_mark_adapter_suspended() will try to block and will never return?
> + err = pm_runtime_force_suspend(dev);
> + if (err < 0)
> + return err;
> +
> return 0;
> }
>
> @@ -1813,6 +1818,10 @@ static int __maybe_unused tegra_i2c_resume(struct device *dev)
> if (err)
> return err;
>
> + err = pm_runtime_force_resume(dev);
> + if (err < 0)
> + return err;
> +
> i2c_mark_adapter_resumed(&i2c_dev->adapter);
>
> return 0;
>
