linux-kernel - Re: [PATCH V2 9/9] i2c: tegra: Add pinctrl support

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Message-ID: <CACRpkdZb-dE0qNtBWQnPzsA0FUTg8ghWzu56Ezjm4p2xA35ukw@mail.gmail.com>
Date:   Wed, 7 Sep 2016 16:17:43 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Jon Hunter <jonathanh@...dia.com>
Cc:     Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Stephen Warren <swarren@...dotorg.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Alexandre Courbot <gnurou@...il.com>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V2 9/9] i2c: tegra: Add pinctrl support

On Fri, Aug 26, 2016 at 3:09 PM, Jon Hunter <jonathanh@...dia.com> wrote:

> On Tegra124/132 the pins for I2C6 are shared with the Display Port AUX
> (DPAUX) channel and on Tegra210 the pins for I2C4 and I2C6 are shared
> with DPAUX1 and DPAUX0, respectively. The multiplexing of the pins is
> handled by a register in the DPAUX and so the Tegra DPAUX driver has
> been updated to register a pinctrl device for managing these pins.
>
> The pins for these particular I2C devices are bound to the I2C device
> prior to probing. However, these I2C devices are in a different power
> partition to the DPAUX devices that own the pins. Hence, it is desirable
> to place the pins in the 'idle' state and allow the DPAUX power
> partition to switch off, when these I2C devices is not in use.
> Therefore, add calls to place the I2C pins in the 'default' and 'idle'
> states when the I2C device is runtime resumed and suspended,
> respectively.
>
> Please note that the pinctrl functions that set the state of the pins
> check to see if the devices has pins associated and will return zero
> if they do not. Therefore, it is safe to call these pinctrl functions
> even for I2C devices that do not have any pins associated.
>
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
> Acked-by: Laxman Dewangan <ldewangan@...dia.com>

This is exactly how I imagined these states being used,
so obviously:
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

Yours,
Linus Walleij