From mboxrd@z Thu Jan  1 00:00:00 1970
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH v2] ARM: dts: armadillo800eva: Split LCD mux and gpio
Date: Fri, 02 Jun 2017 08:53:26 +0300
Message-ID: <38369176.p2s9nCEmhA@avalon>
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To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Simon Horman <horms@verge.net.au>, Magnus Damm <magnus.damm@gmail.com>, Linus Walleij <linus.walleij@linaro.org>, Wolfram Sang <wsa+renesas@sang-engineering.com>, linux-renesas-soc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org
List-Id: linux-gpio@vger.kernel.org

Hi Geert,

Thank you for the patch.

On Thursday 01 Jun 2017 12:27:00 Geert Uytterhoeven wrote:
> Configuration of the lcd0 pinmux group and GPIO hog for the external
> GPIO mux are done using a single device node, causing the "output-high"
> property to be applied to both.  This will fail for the pinmux group,
> but doesn't cause any harm, as the failure is ignored silently.
> 
> However, after "pinctrl: sh-pfc: propagate errors on group config", the
> failure will become fatal, leading to a broken display:
> 
>     sh-pfc e6050000.pin-controller: pin_config_group_set op failed for group
> 102 sh-pfc e6050000.pin-controller: Error applying setting, reverse things
> back sh-pfc e6050000.pin-controller: failed to select default state
> 
> Move the GPIO hog to its own node to fix this.
> 
> Fixes: ffd2f9a5afb730b9 ("ARM: shmobile: armadillo800eva dts: Add pinctrl
> and gpio-hog for lcdc0") Signed-off-by: Geert Uytterhoeven
> <geert+renesas@glider.be>
> ---
> This is a hard dependency for "pinctrl: sh-pfc: propagate errors on
> group config" (https://patchwork.kernel.org/patch/9186713/).
> 
> v2:
>   - Keep the GPIO hog, but move it to its own node, instead of using
>     another level of subnodes.  As the GPIO hog node is not referenced from
>     a pinctrl-0 property, pinconf doesn't fail with "No pin or group
>     provided in DT node".

I like this approach better, it allows us to drive the output instead of 
pulling it up, without requiring a full implementation of output drive control 
in the pfc driver.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  arch/arm/boot/dts/r8a7740-armadillo800eva.dts | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/r8a7740-armadillo800eva.dts
> b/arch/arm/boot/dts/r8a7740-armadillo800eva.dts index
> 297b1f10f7346a9f..8c85d3ee5f5e7bfd 100644
> --- a/arch/arm/boot/dts/r8a7740-armadillo800eva.dts
> +++ b/arch/arm/boot/dts/r8a7740-armadillo800eva.dts
> @@ -273,7 +273,9 @@
>  	lcd0_pins: lcd0 {
>  		groups = "lcd0_data24_0", "lcd0_lclk_1", "lcd0_sync";
>  		function = "lcd0";
> +	};
> 
> +	lcd0_mux {
>  		/* DBGMD/LCDC0/FSIA MUX */
>  		gpio-hog;
>  		gpios = <176 0>;

-- 
Regards,

Laurent Pinchart