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

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Date: Mon, 29 Jan 2024 23:48:27 +0100
From: Andi Shyti <andi.shyti@...nel.org>
To: Thomas Richard <thomas.richard@...tlin.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, 
	Bartosz Golaszewski <brgl@...ev.pl>, Andy Shevchenko <andy@...nel.org>, 
	Tony Lindgren <tony@...mide.com>, Haojian Zhuang <haojian.zhuang@...aro.org>, 
	Vignesh R <vigneshr@...com>, Aaro Koskinen <aaro.koskinen@....fi>, 
	Janusz Krzysztofik <jmkrzyszt@...il.com>, Peter Rosin <peda@...ntia.se>, Vinod Koul <vkoul@...nel.org>, 
	Kishon Vijay Abraham I <kishon@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Tom Joseph <tjoseph@...ence.com>, Lorenzo Pieralisi <lpieralisi@...nel.org>, 
	Krzysztof Wilczyński <kw@...ux.com>, Rob Herring <robh@...nel.org>, 
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org, linux-i2c@...r.kernel.org, 
	linux-phy@...ts.infradead.org, linux-pci@...r.kernel.org, gregory.clement@...tlin.com, 
	theo.lebrun@...tlin.com, thomas.petazzoni@...tlin.com, u-kumar1@...com
Subject: Re: [PATCH v2 03/15] i2c: omap: wakeup the controller during
 suspend() callback

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@...tlin.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
>