linux-kernel - Re: [PATCH V2 2/3] pinctrl: allow concurrent gpio and mux function ownership of pins

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Date:	Wed, 14 Mar 2012 10:27:38 -0700
From:	Olof Johansson <olof@...om.net>
To:	Stephen Warren <swarren@...dotorg.org>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dia.com>,
	Linus Walleij <linus.walleij@...ricsson.com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Colin Cross <ccross@...roid.com>,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-tegra@...r.kernel.org
Subject: Re: [PATCH V2 2/3] pinctrl: allow concurrent gpio and mux function
 ownership of pins

On Mon, Mar 12, 2012 at 12:24:35PM -0600, Stephen Warren wrote:
> On 03/06/2012 03:03 AM, Linus Walleij wrote:
> > On Tue, Mar 6, 2012 at 1:22 AM, Stephen Warren <swarren@...dia.com> wrote:
> > 
> >> Per recent updates to Documentation/gpio.txt, gpiolib drivers should
> >> inform pinctrl when a GPIO is requested. pinctrl then marks that pin as
> >> in-use for that GPIO function.
> >>
> >> When an SoC muxes pins in a group, it's quite possible for the group to
> >> contain e.g. 6 pins, but only 4 of them actually be needed by the HW
> >> module that's mux'd to them. In this case, the other 2 pins could be
> >> used as GPIOs. However, pinctrl marks all the pins within the group as
> >> in-use by the selected mux function. To allow the expected gpiolib
> >> interaction, separate the concepts of pin ownership into two parts: One
> >> for the mux function and one for GPIO usage. Finally, allow those two
> >> ownerships to exist in parallel.
> >>
> >> Signed-off-by: Stephen Warren <swarren@...dia.com>
> > 
> > Good, and 100% in accordance with earlier discussions.
> > Acked-by: Linus Walleij <linus.walleij@...aro.org>
> 
> Linus, now that Grant has ack'd and applied the documentation change
> behind this, could you take this one patch into the pinctrl tree. I
> assume it's 3.5 material. After the 3.4 merge window closes, I'll
> probably come back and ask for a stable pinctrl branch that I can use as
> the basis for a Tegra branch that'll contain patch 3 in this series.
> 
> (Olof, I assume that's the right way to approach this; having Linus
> apply both patches 2/3 in this series to pinctrl is going to make life
> difficult in the Tegra tree, since my outstanding patches to convert
> Tegra to use pinctrl will touch many of the same files as patch 3 in
> this series, in conflicting or dependent ways.)

Yes, that seems like a good way to handle it.


-Olof
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