linux-kernel - Re: [PATCH v6 4/6] reset: Instantiate reset GPIO controller for shared reset-gpios

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Date: Wed, 31 Jan 2024 14:42:17 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Bartosz Golaszewski <brgl@...ev.pl>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>, Banajit Goswami <bgoswami@...cinc.com>, 
	Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
	Rob Herring <robh+dt@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Viresh Kumar <viresh.kumar@...aro.org>, Frank Rowand <frowand.list@...il.com>, 
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org, 
	linux-arm-msm@...r.kernel.org, linux-sound@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-pm@...r.kernel.org, Chris Packham <chris.packham@...iedtelesis.co.nz>, 
	Sean Anderson <sean.anderson@...o.com>
Subject: Re: [PATCH v6 4/6] reset: Instantiate reset GPIO controller for
 shared reset-gpios

On Wed, Jan 31, 2024 at 2:32 PM Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:

> The non-exclusive GPIO was made explicitly for regulators, so it is
> working fine there, but it is broken everywhere else, where the drivers
> do not handle it in sane way as regulator core does.

I looked at it, it's 8 users in the entire kernel that aren't regulators,
so let's put it on the TODO to get rid of those.

> To make it working, either GPIO should be enable-count-aware, to which
> Bartosz was opposing with talks with me, or the subsystem should mimic
> regulators approach. In some way, my patchset is the second way here -
> reset framework subsystem being aware of shared GPIO and handles the
> enable-count, even though it is not using non-exclusive flag.

That's nice, I was thinking if it could be abstracted so the regulator
core can move away from this too?

I guess it may be an issue that regulators are not using Device Tree
exclusively, but also has to deal with a slew of platform_devices:s :/
IIRC that was one of the reasons why it looks as it does.

Maybe reset can only solve this in an elegant way if the solution is
tightly coupled with DT and you have the advantage that you can require
it from day one? (It looks a bit like that to me.)

Yours,
Linus Walleij