[PATCH v2] arm64: dts: mediatek: mt8173-elm-hana: Add vdd-supply to second source trackpad

[Chen-Yu Tsai <wenst@chromium.org>]

The Hana device has a second source option trackpad, but it is missing
its regulator supply. It only works because the regulator is marked as
always-on.

Add the regulator supply, but leave out the post-power-on delay. Instead,
document the post-power-on delay along with the reason for not adding
it in a comment.

Fixes: 689b937bedde ("arm64: dts: mediatek: add mt8173 elm and hana board")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
---
Changes since v1:
- Drop the commented post-power-on-delay-ms property
- Document the delay in a comment
---
 arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi b/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
index 8d1cbc92bce3..ae0379fd42a9 100644
--- a/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
@@ -49,6 +49,14 @@ trackpad2: trackpad@2c {
 		interrupts-extended = <&pio 117 IRQ_TYPE_LEVEL_LOW>;
 		reg = <0x2c>;
 		hid-descr-addr = <0x0020>;
+		/*
+		 * The trackpad needs a post-power-on delay of 100ms,
+		 * but at time of writing, the power supply for it on
+		 * this board is always on. The delay is therefore not
+		 * added to avoid impacting the readiness of the
+		 * trackpad.
+		 */
+		vdd-supply = <&mt6397_vgp6_reg>;
 		wakeup-source;
 	};
 };
-- 
2.47.0.rc1.288.g06298d1525-goog