linux-kernel - Re: [PATCH v5 02/11] i2c: omap: wakeup the controller during suspend() callback

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Date: Wed, 24 Apr 2024 12:24:24 +0200
From: Thomas Richard <thomas.richard@...tlin.com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Andi Shyti <andi.shyti@...nel.org>,
 Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski
 <brgl@...ev.pl>, Tony Lindgren <tony@...mide.com>,
 Aaro Koskinen <aaro.koskinen@....fi>,
 Janusz Krzysztofik <jmkrzyszt@...il.com>, Vignesh R <vigneshr@...com>,
 Peter Rosin <peda@...ntia.se>, Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kw@...ux.com>,
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Siddharth Vadapalli <s-vadapalli@...com>, linux-gpio@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
 linux-i2c@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, gregory.clement@...tlin.com,
 theo.lebrun@...tlin.com, thomas.petazzoni@...tlin.com, u-kumar1@...com,
 Wolfram Sang <wsa+renesas@...g-engineering.com>
Subject: Re: [PATCH v5 02/11] i2c: omap: wakeup the controller during
 suspend() callback

On 4/22/24 21:44, Bjorn Helgaas wrote:
> On Mon, Apr 22, 2024 at 11:40:02AM +0200, Thomas Richard wrote:
>> On 4/19/24 10:47, Andi Shyti wrote:
>>> Hi Thomas,
>>>
>>>> +static int omap_i2c_suspend(struct device *dev)
>>>> +{
>>>> +	/*
>>>> +	 * If the controller is autosuspended, there is no way to wakeup it once
>>>> +	 * runtime pm is disabled (in suspend_late()).
>>>> +	 * But a device may need the controller up during suspend_noirq() or
>>>> +	 * resume_noirq().
>>>> +	 * Wakeup the controller while runtime pm is enabled, so it is available
>>>> +	 * until its suspend_noirq(), and from resume_noirq().
>>>> +	 */
>>>> +	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)
>>>
>>> If you don't have CONFIG_PM_SLEEP, though, this doesn't compile.
>>
>> Hello Andi,
>>
>> Yes indeed, the __maybe_unused attribute is missing for
>> omap_i2c_suspend() and omap_i2c_resume().
> 
> Isn't there a way to avoid having to use the __maybe_unused attribute?
> 
> E.g., use DEFINE_SIMPLE_DEV_PM_OPS() as is done by these:
> 
>   82f9cefadac4 ("serial: 8250_exar: switch to DEFINE_SIMPLE_DEV_PM_OPS()")
>   f243df0a0be0 ("media: platform: rzg2l-cru: rzg2l-csi2: Switch to RUNTIME_PM_OPS()")
>   6ccc22a5afcb ("net: ravb: Switch to SYSTEM_SLEEP_PM_OPS()/RUNTIME_PM_OPS() and pm_ptr()")

Yes you're right, I don't need the __maybe_unused attribute if I use
NOIRQ_SYSTEM_SLEEP_PM_OPS().

By the way I can add a patch in the series to remove all the
__maybe_unused attributes of this driver.

Regards,

-- 
Thomas Richard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com