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

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Date: Sun, 28 Jan 2024 01:12:50 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Thomas Richard <thomas.richard@...tlin.com>
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 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?

Worst case using if (of_machine_is_compatible("my,machine"))...

Yours,
Linus Walleij