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From: Linus Walleij <linus.walleij@linaro.org>
To: Rob Herring <robh+dt@kernel.org>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>,
	Mark Brown <broonie@kernel.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Tero Kristo <t-kristo@ti.com>, Maxime Ripard <mripard@kernel.org>,
	Philipp Zabel <p.zabel@pengutronix.de>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>
Subject: Re: [RFC v2 0/2] gpio: Support for shared GPIO lines on boards
Date: Tue, 5 Nov 2019 10:58:03 +0100	[thread overview]
Message-ID: <CACRpkdbiG5mt3WGEeHWsu-L3dzQJUQjxjGwQXK0cLgZNZ74yWg@mail.gmail.com> (raw)
In-Reply-To: <CAL_JsqJbhG+-zVs9bjHg8asGuM1+FNnGJ0xx7qcPBwuRX35ijw@mail.gmail.com>

On Mon, Nov 4, 2019 at 8:11 PM Rob Herring <robh+dt@kernel.org> wrote:
> [Peter]
> > The device needs the RST line to be high, otherwise it is not
> > accessible. If it does not have reset control how can we make sure that
> > the GPIO line is in correct state?
>
> Just like the reset code, drivers register their use of the reset and
> the core tracks users and prevents resetting when not safe. Maybe the
> reset subsystem needs to learn about GPIO resets. (...)

I agree. Certainly the reset subsystem can do what the regulator
subsystem is already doing: request the GPIO line nonexclusive
and handle any reference counting and/or quirks that are needed
in a hypothetical drivers/reset/reset-gpio.c driver.

There is no such driver today, just a "reset" driver in
drivers/power/reset that resets the whole system.

But I see no problem in creating a proper reset driver in drivers/reset
to handle a few peripherals with a shared GPIO reset line.

Yours,
Linus Walleij

  reply	other threads:[~2019-11-05  9:58 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-30 12:04 [RFC v2 0/2] gpio: Support for shared GPIO lines on boards Peter Ujfalusi
2019-10-30 12:04 ` [RFC v2 1/2] dt-bindings: gpio: Add binding document for shared GPIO Peter Ujfalusi
2019-10-30 12:04 ` [RFC v2 2/2] gpio: Add new driver for handling 'shared' gpio lines on boards Peter Ujfalusi
2019-10-30 13:12 ` [RFC v2 0/2] gpio: Support for shared GPIO " Rob Herring
2019-10-30 13:32   ` Peter Ujfalusi
2019-10-30 13:51     ` Philipp Zabel
2019-10-30 14:03       ` Peter Ujfalusi
2019-10-30 14:17     ` Mark Brown
2019-10-30 14:31       ` Peter Ujfalusi
2019-10-30 18:49         ` Rob Herring
2019-10-31  8:01           ` Peter Ujfalusi
2019-11-01 13:46             ` Rob Herring
2019-11-01 15:21               ` Peter Ujfalusi
2019-11-04 19:11                 ` Rob Herring
2019-11-05  9:58                   ` Linus Walleij [this message]
2019-11-05 11:15                     ` Peter Ujfalusi
2019-11-05 12:15                     ` Grygorii Strashko
2019-11-05 12:32                       ` Peter Ujfalusi
2019-11-05 18:07                         ` Grygorii Strashko
2019-11-06  9:23                           ` Peter Ujfalusi
2019-11-06 10:00                             ` Philipp Zabel
2019-11-05 12:17                   ` Peter Ujfalusi
2019-11-18 12:15 ` Enrico Weigelt, metux IT consult
2019-11-18 13:38   ` Philipp Zabel
2019-11-18 14:00   ` Peter Ujfalusi

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