Re: [PATCH v2 03/15] i2c: omap: wakeup the controller during suspend() callback

Andi Shyti
2024-01-29T22:48:35Z

Hi Thomas,

On Fri, Jan 26, 2024 at 03:36:45PM +0100, Thomas Richard wrote:
> A device may need the controller up during suspend_noirq() or
> resume_noirq().
> But if the controller is autosuspended, there is no way to wakeup it during
> suspend_noirq() or resume_noirq() because runtime pm is disabled at this
> time.
>
> The suspend() callback wakes up the controller, so it is available until
> its suspend_noirq() callback (pm_runtime_force_suspend()).
> During the resume, it's restored by resume_noirq() callback
> (pm_runtime_force_resume()). Then resume() callback enables autosuspend.
>
> So the controller is up during a little time slot in suspend and resume
> sequences even if it's not used.

Looks good, can I ask you to put this in a comment below? It's
not completely straight forward.

Thanks,
Andi

> Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
> ---
> drivers/i2c/busses/i2c-omap.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index 42165ef57946..cc9841cb08f1 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -1575,9 +1575,23 @@ static int __maybe_unused omap_i2c_runtime_resume(struct device *dev)
> return 0;
> }
>
> +static int omap_i2c_suspend(struct device *dev)
> +{
> + return pm_runtime_resume_and_get(dev);
> +}
> +
> +static int omap_i2c_resume(struct device *dev)
> +{
> + pm_runtime_mark_last_busy(dev);
> + pm_runtime_put_autosuspend(dev);
> +
> + return 0;
> +}
> +
> static const struct dev_pm_ops omap_i2c_pm_ops = {
> SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> pm_runtime_force_resume)
> + SET_SYSTEM_SLEEP_PM_OPS(omap_i2c_suspend, omap_i2c_resume)
> SET_RUNTIME_PM_OPS(omap_i2c_runtime_suspend,
> omap_i2c_runtime_resume, NULL)
> };
>
> --
> 2.39.2
>