From: Linus Walleij <linus.walleij@linaro.org>
To: Stephen Warren <swarren@wwwdotorg.org>
Cc: Linus Walleij <linus.walleij@stericsson.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Stephen Warren <swarren@nvidia.com>,
Anmar Oueja <anmar.oueja@linaro.org>
Subject: Re: [PATCH v2] pinctrl: document semantics vs GPIO
Date: Mon, 17 Sep 2012 10:58:54 +0200 [thread overview]
Message-ID: <CACRpkdYhy4k_JFckfYPP3ijku2O_cFQQr5810FAaje0xNr1FCw@mail.gmail.com> (raw)
In-Reply-To: <5053668B.6020604@wwwdotorg.org>
On Fri, Sep 14, 2012 at 7:16 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
> On 09/14/2012 07:49 AM, Linus Walleij wrote:
>> +If a pin control driver and a GPIO driver is dealing with the same pins
>> +and the use cases involve multiplexing, you MUST implement the pin controller
>> +as a back-end for the GPIO driver like this.
>
> I might add one caveat to that:
>
> ==========
> , unless your HW design is such that the GPIO controller can override
> the pin controller's mux state, without the need for any such interaction.
> ==========
OK I buy that, so added this paragraph (slightly rephrased) and pused
for next.
> In the future, I wonder if someone might want the following caveat,
>
> ==========
> , unless you require that all boards (or device trees) define a system
> hog pinmux configuration that muxes all required GPIO signals as desired.
> ==========
>
> ... which might be appropriate for HW where GPIO-vs-special-function
> selection is performed in the pinmux controller itself, per-pin. Perhaps
> this is the OMAP special case you mentioned before?
Yeah :-/
I worry about exploding complexity here, so we need to think
about this a bit more...
Linus
prev parent reply other threads:[~2012-09-17 8:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-14 13:49 [PATCH v2] pinctrl: document semantics vs GPIO Linus Walleij
2012-09-14 14:35 ` Domenico Andreoli
2012-09-14 17:16 ` Stephen Warren
2012-09-17 8:58 ` Linus Walleij [this message]
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