linux-kernel - [PATCH] ARM: dts: at91: nattis: initialize the BLON pin as output-low early

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Date:   Tue, 20 Nov 2018 21:20:43 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Peter Rosin <peda@...ntia.se>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>
Subject: [PATCH] ARM: dts: at91: nattis: initialize the BLON pin as output-low
 early

The pwm-backlight driver initializes BLON (the enable gpio) to
output-high if the gpio is input on probe. Initializing the gpio
to output-low before the driver probes prevents this action by
the pwm-backlight driver and gets rid of a nasty blink of full
backlight with an uninitialized panel.

Signed-off-by: Peter Rosin <peda@...ntia.se>
---
 arch/arm/boot/dts/at91-nattis-2-natte-2.dts | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm/boot/dts/at91-nattis-2-natte-2.dts b/arch/arm/boot/dts/at91-nattis-2-natte-2.dts
index 911d2c7c1500..0f6d335125e2 100644
--- a/arch/arm/boot/dts/at91-nattis-2-natte-2.dts
+++ b/arch/arm/boot/dts/at91-nattis-2-natte-2.dts
@@ -60,6 +60,8 @@
 
 		power-supply = <&bl_reg>;
 		enable-gpios = <&pioA 20 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_blon>;
 	};
 
 	panel: panel {
@@ -164,6 +166,12 @@
 				      (AT91_PINCTRL_OUTPUT |
 				       AT91_PINCTRL_OUTPUT_VAL(0))>;
 		};
+
+		pinctrl_blon: blon {
+			atmel,pins = <AT91_PIOA 20 AT91_PERIPH_GPIO
+				      (AT91_PINCTRL_OUTPUT |
+				       AT91_PINCTRL_OUTPUT_VAL(0))>;
+		};
 	};
 };
 
-- 
2.11.0