linux-kernel - Re: [PATCH v5 1/2] mfd: arizona: Update reset pin to use GPIOD

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Date:   Sat, 24 Mar 2018 15:32:05 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc:     Lee Jones <lee.jones@...aro.org>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        patches@...nsource.cirrus.com
Subject: Re: [PATCH v5 1/2] mfd: arizona: Update reset pin to use GPIOD

On Mon, Mar 12, 2018 at 4:52 PM, Charles Keepax
<ckeepax@...nsource.cirrus.com> wrote:

> Now GPIOD has support for both pdata systems and for non-standard DT
> bindings the Arizona reset GPIO can be converted to use it. Worth
> noting gpiod_set_raw_value_cansleep is used to match the behaviour
> of the old GPIOs. This is because the part is fairly widely used and
> it is unknown how many DTs are correctly setting active low through
> device tree, so to avoid breaking any existing users it is best to
> match the previous behaviour.
>
> Signed-off-by: Charles Keepax <ckeepax@...nsource.cirrus.com>
> ---
>
> Changes since v4:
>  - Don't use a switch statement for handling return values
>  - Add some comments to the handling for the older binding
>  - Use gpiod_set_raw_value_cansleep to avoid potential breakage
>
> I have also removed Linus's reviewed-by was a bit border line but
> I felt there have probably been enough code changes since he gave
> it that it was probably safer to remove it.

It's fine.
Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

The use of gpiod_set_raw* should be done with caution, but this
is one of the cases where we need to take out the big hammer to
make sure things stay compatible.

I haven't read why it is like so but I guess because the right flags
in the device tree can not be guaranteed?

Yours,
Linus Walleij