linux-kernel - [PATCH] DTS: ARM: gta04: remove legacy spi-cs-high to make display work again

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Date:   Sat, 12 Dec 2020 10:55:25 +0100
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Benoît Cousson <bcousson@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     linux-omap@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, letux-kernel@...nphoenux.org,
        Andreas Kemnade <andreas@...nade.info>,
        "H. Nikolaus Schaller" <hns@...delico.com>, stable@...r.kernel.org
Subject: [PATCH] DTS: ARM: gta04: remove legacy spi-cs-high to make display work again

This reverts

commit f1f028ff89cb ("DTS: ARM: gta04: introduce legacy spi-cs-high to make display work again")

which had to be intruduced after

commit 6953c57ab172 ("gpio: of: Handle SPI chipselect legacy bindings")

broke the GTA04 display. This contradicted the data sheet but was the only
way to get it as an spi client operational again.

The panel data sheet defines the chip-select to be active low.

Now, with the arrival of

commit 766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors")

the logic of interaction between spi-cs-high and the gpio descriptor flags
has been changed a second time, making the display broken again. So we have
to remove the original fix which in retrospect was a workaround of a bug in
the spi subsystem and not a feature of the panel or bug in the device tree.

With this fix the device tree is back in sync with the data sheet and
spi subsystem code.

Fixes: 766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors")
CC: stable@...r.kernel.org
Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
---
 arch/arm/boot/dts/omap3-gta04.dtsi | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm/boot/dts/omap3-gta04.dtsi b/arch/arm/boot/dts/omap3-gta04.dtsi
index c8745bc800f71..003202d129907 100644
--- a/arch/arm/boot/dts/omap3-gta04.dtsi
+++ b/arch/arm/boot/dts/omap3-gta04.dtsi
@@ -124,7 +124,6 @@ lcd: td028ttec1@0 {
 			spi-max-frequency = <100000>;
 			spi-cpol;
 			spi-cpha;
-			spi-cs-high;
 
 			backlight= <&backlight>;
 			label = "lcd";
-- 
2.26.2