[RFC PATCH v3 3/3] arm64: dts: rockchip: fix power-off on Firefly-RK3399

[Yaozhong Li <yaozhonguwl@gmail.com>]

poweroff on this board drops the rails and immediately brings them back
up, so it reboots instead of staying off and U-Boot reports a power-on
reset.

Firefly's BSP drives GPIO1_D0 high while the system runs and low during
shutdown, before writing the RK808's shutdown bit. Mainline does not
describe GPIO1_D0 at all, so nothing drives it and the shutdown does not
stick. Describe it in the PMIC node, with the settle time the vendor
uses.

The BSP releases GPIO1_B5 in the same sequence, and in testing the board
came back up when that pin was still high as the shutdown bit was
written. Mainline describes GPIO1_B5 as the backlight enable GPIO.
pwm-backlight drives its enable GPIO low whenever it turns the backlight
off, including from its shutdown callback in device_shutdown(), which
runs before the PMIC's power-off prepare handler. That pin is therefore
left to the backlight.

Fixes: 171582e00db1 ("arm64: dts: rockchip: add support for firefly-rk3399 board")
Assisted-by: LLM
Signed-off-by: Yaozhong Li <yaozhonguwl@gmail.com>
---
 arch/arm64/boot/dts/rockchip/rk3399-firefly.dts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts b/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
index 0568dfa..210e4cb 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
@@ -327,6 +327,8 @@ rk808: pmic@1b {
 		pinctrl-names = "default";
 		pinctrl-0 = <&pmic_int_l>;
 		system-power-controller;
+		power-hold-gpios = <&gpio1 RK_PD0 GPIO_ACTIVE_HIGH>;
+		power-hold-delay-ms = <200>;
 		wakeup-source;
 
 		vcc1-supply = <&vcc_sys>;
-- 
2.55.0.windows.3