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Date: Mon, 29 Jan 2024 23:48:27 +0100
From: Andi Shyti <andi.shyti@kernel.org>
To: Thomas Richard <thomas.richard@bootlin.com>
Cc: Linus Walleij <linus.walleij@linaro.org>, 
	Bartosz Golaszewski <brgl@bgdev.pl>, Andy Shevchenko <andy@kernel.org>, 
	Tony Lindgren <tony@atomide.com>, Haojian Zhuang <haojian.zhuang@linaro.org>, 
	Vignesh R <vigneshr@ti.com>, Aaro Koskinen <aaro.koskinen@iki.fi>, 
	Janusz Krzysztofik <jmkrzyszt@gmail.com>, Peter Rosin <peda@axentia.se>, Vinod Koul <vkoul@kernel.org>, 
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	theo.lebrun@bootlin.com, thomas.petazzoni@bootlin.com, u-kumar1@ti.com
Subject: Re: [PATCH v2 03/15] i2c: omap: wakeup the controller during
 suspend() callback
Message-ID: <hqnxyffdsiqz5t43bexcqrwmynpjubxbzjchjaagxecso75dc7@y7lznovxg3go>
References: <20240102-j7200-pcie-s2r-v2-0-8e4f7d228ec2@bootlin.com>
 <20240102-j7200-pcie-s2r-v2-3-8e4f7d228ec2@bootlin.com>
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In-Reply-To: <20240102-j7200-pcie-s2r-v2-3-8e4f7d228ec2@bootlin.com>

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
>