linux-kernel - Re: [PATCH 01/14] gpio: pca953x: move suspend/resume to suspend_noirq/resume

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Date: Thu, 8 Feb 2024 17:19:25 +0100
From: Thomas Richard <thomas.richard@...tlin.com>
To: Linus Walleij <linus.walleij@...aro.org>
Cc: Tony Lindgren <tony@...mide.com>, Bartosz Golaszewski <brgl@...ev.pl>,
 Andy Shevchenko <andy@...nel.org>, 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>, 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 01/14] gpio: pca953x: move suspend/resume to
 suspend_noirq/resume_noirq

On 1/28/24 01:12, Linus Walleij wrote:
> On Fri, Jan 19, 2024 at 6:01 PM Thomas Richard
> <thomas.richard@...tlin.com> wrote:
>> On 1/16/24 08:43, Tony Lindgren wrote:
>>> * Thomas Richard <thomas.richard@...tlin.com> [240115 16:16]:
>>>> Some IOs can be needed during suspend_noirq/resume_noirq.
>>>> So move suspend/resume callbacks to noirq.
>>>
>>> So have you checked that the pca953x_save_context() and restore works
>>> this way? There's i2c traffic and regulators may sleep.. I wonder if
>>> you instead just need to leave gpio-pca953x enabled in some cases
>>> instead?
>>>
>>
>> Yes I tested it, and it works (with my setup).
>> But this patch may have an impact for other people.
>> How could I leave it enabled in some cases ?
> 
> I guess you could define both pca953x_suspend() and
> pca953x_suspend_noirq() and selectively bail out on one
> path on some systems?

Yes.

What do you think if I use a property like for example "ti,pm-noirq" to
select the right path ?
Is a property relevant for this use case ?

Regards,

> 
> Worst case using if (of_machine_is_compatible("my,machine"))...
> 
> Yours,
> Linus Walleij
-- 
Thomas Richard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com