linux-kernel - Re: [PATCH v4 02/18] pinctrl: pinctrl-single: move suspend()/resume() callbacks to noirq

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Date: Wed, 20 Mar 2024 09:37:21 +0100
From: Thomas Richard <thomas.richard@...tlin.com>
To: Dhruva Gole <d-gole@...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>, Andi Shyti
 <andi.shyti@...nel.org>, Peter Rosin <peda@...ntia.se>,
 Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
 Philipp Zabel <p.zabel@...gutronix.de>,
 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,
 Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH v4 02/18] pinctrl: pinctrl-single: move suspend()/resume()
 callbacks to noirq

On 3/20/24 08:44, Dhruva Gole wrote:
> Hi,
> 
> On Mar 04, 2024 at 16:35:45 +0100, Thomas Richard wrote:
>> The goal is to extend the active period of pinctrl.
>> Some devices may need active pinctrl after suspend() and/or before
>> resume().
>> So move suspend()/resume() to suspend_noirq()/resume_noirq() in order to
>> have active pinctrl until suspend_noirq() (included), and from
>> resume_noirq() (included).
>>
>> The deprecated API has been removed to use the new one (dev_pm_ops struct).
>>
>> No need to check the pointer returned by dev_get_drvdata(), as
>> platform_set_drvdata() is called during the probe.
>>
>> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
>> Signed-off-by: Thomas Richard <thomas.richard@...tlin.com>
>> ---
> 
> I was planning to do this but didn't see particular benefit to it. Do
> you see the benefit on your specific device? Can you help me understand
> how? Not against the patch, just curious.

Hello Dhruva,

We need this patch to support suspend to ram for the PCIe on J7200.
In root complex mode, a gpio is used to reset endpoints.
This gpio shall be managed during suspend_noirq and resume_noirq stages.
On J7200 this gpio is on a gpio expander.
So we need this patch to restore pinctrl to be able to do i2c accesses
in noirq stages.

Best Regards,

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