[PATCH v4 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. When pwm-backlight is
not bound, nothing claims the pin; on this board it is then an input
reading low, which also lets the shutdown stick, although that is not
guaranteed on every board. The 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