linux-kernel - [PATCH RFC] arm64: dts: mediatek: mt8195-cherry: Remove keyboard-backlight node

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Message-Id: <20240715-cros-backlight-dt-probe-v1-1-0b5afe64c94b@collabora.com>
Date: Mon, 15 Jul 2024 12:09:34 -0400
From: Nícolas F. R. A. Prado <nfraprado@...labora.com>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Matthias Brugger <matthias.bgg@...il.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>, 
 Thomas Weißschuh <linux@...ssschuh.net>, 
 Tzung-Bi Shih <tzungbi@...nel.org>, kernel@...labora.com, 
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
 Nícolas F. R. A. Prado <nfraprado@...labora.com>
Subject: [PATCH RFC] arm64: dts: mediatek: mt8195-cherry: Remove
 keyboard-backlight node

Commit 970c3a6b7aa3 ("mfd: cros_ec: Register keyboard backlight
subdevice") introduced support for detecting keyboard backlight
fuctionality through communication with the ChromeOS EC. This means that
the DT node is no longer used. Remove the unneeded node.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>
---
Different CrosEC FW versions could potentially not support discovering
the keyboard backlight functionality, but I've tested both a recent

  tomato_v2.0.23149-099cd3e539 tomato_15699.72.0 2024-01-03

and an old

  tomato_v2.0.10686-234e646fd8 tomato_14268.0.0 2021-10-07

version on mt8195-cherry-tomato and on both relying only on the
discoverability works. I've tested on both tomato-r2 and tomato-r3. I
have not tested on dojo, however, as I don't have access to it.

My motivation to remove the node is because the DT kselftest expects DT
nodes that can match to a driver to be probed, and with the "breaking"
commit, the DT node goes unprobed which results in a failure:

  not ok 225 /soc/spi@...0a000/ec@...eyboard-backlight

I can also solve this in a different way, by adding this driver to the
ignore list of the test. But this solution seemed better as the DT
isn't meant to describe devices that can be discovered at run time
anyway.
---
 arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
index fe5400e17b0f..20dfa18c9dda 100644
--- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
@@ -1228,10 +1228,6 @@ cros_ec: ec@0 {
 		spi-max-frequency = <3000000>;
 		wakeup-source;

-		keyboard-backlight {
-			compatible = "google,cros-kbd-led-backlight";
-		};
-
 		i2c_tunnel: i2c-tunnel {
 			compatible = "google,cros-ec-i2c-tunnel";
 			google,remote-bus = <0>;

---
base-commit: 91e3b24eb7d297d9d99030800ed96944b8652eaf
change-id: 20240715-cros-backlight-dt-probe-7754a832ad60

Best regards,
-- 
Nícolas F. R. A. Prado <nfraprado@...labora.com>