[PATCH] arm64: dts: mediatek: mt8186-corsola: Fix IT6505 reset line polarity

[PATCH] arm64: dts: mediatek: mt8186-corsola: Fix IT6505 reset line polarity

[Chen-Yu Tsai]

The reset line of the IT6505 bridge chip is active low, not active high.
It was incorrectly inverted in the device tree as the implementation at
the time incorrectly inverted the polarity in its driver, due to a prior
device having an inline inverting level shifter.

Fix the polarity now while the external display pipeline is incomplete,
thereby avoiding any impact to running systems.

A matching fix for the driver should be included if this change is
backported.

Fixes: 8855d01fb81f ("arm64: dts: mediatek: Add MT8186 Krabby platform based Tentacruel / Tentacool")
Cc: <stable@vger.kernel.org>
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
The matching driver change can be found at

    https://lore.kernel.org/all/20241029095411.657616-1-wenst@chromium.org/

 arch/arm64/boot/dts/mediatek/mt8186-corsola.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/mediatek/mt8186-corsola.dtsi b/arch/arm64/boot/dts/mediatek/mt8186-corsola.dtsi
index e3b58641f2c9..43c83620e479 100644
--- a/arch/arm64/boot/dts/mediatek/mt8186-corsola.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8186-corsola.dtsi
@@ -422,7 +422,7 @@ it6505dptx: dp-bridge@5c {
 		#sound-dai-cells = <0>;
 		ovdd-supply = <&mt6366_vsim2_reg>;
 		pwr18-supply = <&pp1800_dpbrdg_dx>;
-		reset-gpios = <&pio 177 GPIO_ACTIVE_HIGH>;
+		reset-gpios = <&pio 177 GPIO_ACTIVE_LOW>;
 
 		ports {
 			#address-cells = <1>;
-- 
2.47.0.163.g1226f6d8fa-goog

Re: [PATCH] arm64: dts: mediatek: mt8186-corsola: Fix IT6505 reset line polarity

[AngeloGioacchino Del Regno]

On Tue, 29 Oct 2024 18:02:25 +0800, Chen-Yu Tsai wrote:
> The reset line of the IT6505 bridge chip is active low, not active high.
> It was incorrectly inverted in the device tree as the implementation at
> the time incorrectly inverted the polarity in its driver, due to a prior
> device having an inline inverting level shifter.
> 
> Fix the polarity now while the external display pipeline is incomplete,
> thereby avoiding any impact to running systems.
> 
> [...]

Applied to v6.12-next/dts64, thanks!

[1/1] arm64: dts: mediatek: mt8186-corsola: Fix IT6505 reset line polarity
      commit: fbcc95fceb6d179dd150df2dc613dfd9b013052c

Cheers,
Angelo