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

From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Lee Jones <lee.jones@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	<patches@opensource.cirrus.com>
Subject: Re: [PATCH v5 1/2] mfd: arizona: Update reset pin to use GPIOD
Date: Mon, 26 Mar 2018 09:34:04 +0100	[thread overview]
Message-ID: <20180326083404.ewogeas2rdgbfvhh@localhost.localdomain> (raw)
In-Reply-To: <CACRpkdY396hwrZtAqH=L8nvrr_f5An9zF+EFhO=4mz4XSc45=A@mail.gmail.com>

On Sat, Mar 24, 2018 at 03:32:05PM +0100, Linus Walleij wrote:
> On Mon, Mar 12, 2018 at 4:52 PM, Charles Keepax
> <ckeepax@opensource.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@opensource.cirrus.com>
> > ---
> 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?
> 

Exactly yes there are a lot of these parts out there and since
they never required the DT flags to be set correctly before I
very much doubt all those DTs are set correctly.

Thanks,
Charles