[RFC PATCH 0/3] Fix poweroff restarting the board on Firefly-RK3399

[RFC PATCH 0/3] Fix poweroff restarting the board on Firefly-RK3399

[Yaozhong Li]

Sent as an RFC: the open questions below are about where this belongs and
what the property should be called, and the patched kernel itself has not
been booted on hardware yet (see Testing).

On the Firefly-RK3399, "poweroff" drops the rails and immediately brings
them back up, so the board reboots instead of staying off. U-Boot reports
the result as a power-on reset.

Firefly's BSP drives two SoC pins low during shutdown, before writing the
RK808's shutdown bit: GPIO1_D0 and GPIO1_B5. Mainline does not describe
GPIO1_D0 at all, and describes GPIO1_B5 as the backlight enable GPIO,
although the vendor's own backlight node has no enable GPIO. Nothing
therefore releases either line at power-off.

What was established on the board is the sequence, not what happens inside
the PMIC: the shutdown sticks only when GPIO1_D0 goes from high to low
during power-off prepare, with GPIO1_B5 low, and the shutdown bit written
after a settle delay. Leaving GPIO1_B5 asserted makes the board come back
up even when GPIO1_D0 is released correctly, which is why the backlight
cannot keep that pin. Why the board powers back up in the failing cases is
not explained here.

Why not gpio-poweroff
---------------------

gpio-poweroff drives the line active, back to inactive, then active again,
waits timeout-ms and then WARN()s on the assumption that it is itself
performing the power off, and it registers at SYS_OFF_MODE_POWER_OFF. Here
the RK808 performs the power off from its own POWER_OFF_PREPARE handler,
the lines only have to be released and left released, and there are two of
them.

rk3188-bqedison2qc.dts does drive a pwr_hold pin from gpio-poweroff, which
works there because pulling that line low is by itself enough to cut the
power: the board is gone during the first active-delay-ms and the rest of
the sequence never runs. That is not the case here - driving a line low at
runtime, with no PMIC access at all, left this board running for the 10 s
it was observed.

Open questions
--------------

1. Does this belong in the PMIC driver? Releasing the lines inside
   rk808_power_off() keeps the ordering against the I2C write explicit and
   needs no second handler, but it does put board level wiring into the
   PMIC MFD driver. A separate driver registering at POWER_OFF_PREPARE
   with a higher priority would work too.

2. Property naming. power-hold-gpios follows the <function>-gpios
   convention, like the existing dvs-gpios in this binding. If the binding
   should describe Rockchip specific board wiring rather than an RK8xx
   feature, rockchip,power-hold-gpios would be more appropriate. The
   vendor DT calls these pins pmic,stby-gpio and pmic,hold-gpio.

3. Should the DT also carry a pinctrl group for the pins, as the vendor DT
   does? It works here without one, so nothing untested was added.

4. Dropping the backlight enable-gpios is required for the sequence to
   work, but it also means the backlight loses an enable GPIO it may
   genuinely have wanted. The vendor's backlight node has none and is
   disabled entirely, which suggests the mainline property was a mistake,
   but nobody here has the schematic to confirm it.

Testing
-------

Tested on a Firefly-RK3399 (4 GB, RK808) with the shutdown captured on the
debug UART at 1500000 8N1. A run counts as "stayed off" only if the
console produced nothing for 150 s and there was no ICMP reply and no USB
gadget afterwards; a restart is unambiguous because "DDR Version" and
"Reset cause: POR" appear on the console within seconds.

The patched kernel has NOT been booted: CONFIG_MFD_RK8XX is built in on
the test system and a full kernel build did not fit on it. The series
compiles (aarch64, W=1, no warnings). dt_binding_check passes; dtbs_check
reports only the pre-existing usb2phy diagnostics for this board,
reproduced unchanged on the unpatched tree. The functional evidence comes
from an out-of-tree module using the same gpiod array consumer name, the
same GPIOD_OUT_HIGH, the same per-descriptor gpiod_set_value_cansleep()
loop and the same msleep() as this series, against a device tree carrying
exactly these properties. It registers at POWER_OFF_PREPARE with
SYS_OFF_PRIO_HIGH + 1, immediately ahead of the RK808 handler. It does not
reproduce the RK808 acquiring the array at probe time.

Every run started from a cold boot with both pins at their reset state
(inputs, low), verified by reading the GPIO registers beforehand:

  both lines, as in this series:            3 of 3 stayed off
  GPIO1_D0 only, GPIO1_B5 left low:        3 of 3 stayed off
  GPIO1_B5 only, GPIO1_D0 left low:        0 of 2 stayed off
  GPIO1_D0 released, GPIO1_B5 left high:   0 of 2 stayed off
  nothing driven (mainline today):         restarts after about 2 s

Note the second and third rows: on this particular board pwm-backlight
does not bind, so GPIO1_B5 stays an input and describing GPIO1_D0 alone
was enough here. That is not true in general, which is why both lines are
described and the backlight property is dropped.

The 200 ms is the value the vendor uses; the threshold was not
characterised. The gpiod calls and msleep() run in POWER_OFF_PREPARE,
which is allowed to sleep - the msleep() was measured at 200 to 201 ms on
the console timestamps.

One early run appeared to show GPIO1_B5 alone was sufficient. It had
reached that state through a warm reboot rather than a cold boot, so the
pin states were not what they were assumed to be; it is excluded, and it
is not fully explained by the description above either.


This series was prepared with AI assistance (Claude); the analysis and
the measurements on the board were reviewed by the author.

Yaozhong Li (3):
  dt-bindings: mfd: rk808: add board level power hold GPIOs
  mfd: rk8xx: release the power hold GPIOs before powering off
  arm64: dts: rockchip: fix power-off on Firefly-RK3399

 .../bindings/mfd/rockchip,rk808.yaml          | 20 +++++++++++++
 .../boot/dts/rockchip/rk3399-firefly.dts      |  4 ++-
 drivers/mfd/rk8xx-core.c                      | 29 +++++++++++++++++++
 include/linux/mfd/rk808.h                     |  4 +++
 4 files changed, 56 insertions(+), 1 deletion(-)

-- 
2.55.0.windows.3

[RFC PATCH 1/3] dt-bindings: mfd: rk808: add board level power hold GPIOs

[Yaozhong Li]

Some boards route "power hold" lines from the SoC into the board's power
circuitry. Those lines have to be held asserted while the system is
running and released before the PMIC shutdown request is written; with any
of them left asserted the rails drop and then come back up.

Add power-hold-gpios to describe those lines and power-hold-delay-ms for
the settle time.

Signed-off-by: Yaozhong Li <yaozhonguwl@gmail.com>
---
 .../bindings/mfd/rockchip,rk808.yaml          | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/rockchip,rk808.yaml b/Documentation/devicetree/bindings/mfd/rockchip,rk808.yaml
index 50dfffa..00cbb27 100644
--- a/Documentation/devicetree/bindings/mfd/rockchip,rk808.yaml
+++ b/Documentation/devicetree/bindings/mfd/rockchip,rk808.yaml
@@ -43,6 +43,23 @@ properties:
 
   system-power-controller: true
 
+  power-hold-gpios:
+    minItems: 1
+    maxItems: 2
+    description:
+      Board level power hold lines driven by the SoC. They have to be held
+      asserted while the system is running and released before the PMIC
+      shutdown request is written; with any of them left asserted the rails
+      drop and then come back up. A line left asserted by another consumer
+      therefore defeats the sequence, so every line involved must be listed
+      here.
+
+  power-hold-delay-ms:
+    default: 0
+    description:
+      Time to wait after releasing power-hold-gpios before the shutdown
+      request is written, to let the lines settle.
+
   wakeup-source:
     type: boolean
     description:
@@ -113,6 +130,9 @@ properties:
         unevaluatedProperties: false
     unevaluatedProperties: false
 
+dependencies:
+  power-hold-delay-ms: [ power-hold-gpios ]
+
 required:
   - compatible
   - reg
-- 
2.55.0.windows.3

[RFC PATCH 2/3] mfd: rk8xx: release the power hold GPIOs before powering off

[Yaozhong Li]

rk808_power_off() writes the PMIC's shutdown bit directly. On boards with
"power hold" lines driven by the SoC, a shutdown performed this way does
not stick: the rails drop and immediately come back up, so the board
restarts instead of staying off. U-Boot reports the result as a power-on
reset.

Take those lines as an optional GPIO array, hold them asserted while the
system runs and release them - waiting power-hold-delay-ms - before
writing the shutdown bit. Device trees without the property retain the
existing behaviour.

Releasing every described line matters: on a Firefly-RK3399 the board
stays off when both lines described for it are released, whereas releasing
GPIO1_D0 while GPIO1_B5 is left asserted makes it come back up.

Signed-off-by: Yaozhong Li <yaozhonguwl@gmail.com>
---
 drivers/mfd/rk8xx-core.c  | 29 +++++++++++++++++++++++++++++
 include/linux/mfd/rk808.h |  4 ++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/mfd/rk8xx-core.c b/drivers/mfd/rk8xx-core.c
index 3dcf6ab..fd1efbb 100644
--- a/drivers/mfd/rk8xx-core.c
+++ b/drivers/mfd/rk8xx-core.c
@@ -11,6 +11,8 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
 #include <linux/mfd/rk808.h>
 #include <linux/mfd/core.h>
@@ -703,6 +705,24 @@ static int rk808_power_off(struct sys_off_data *data)
 	default:
 		return NOTIFY_DONE;
 	}
+
+	/*
+	 * Some boards route "power hold" lines from the SoC into the board's
+	 * power circuitry. They have to be held asserted while the system is
+	 * running and released before the PMIC shutdown request is written:
+	 * with any of them left asserted, the rails drop and then come back
+	 * up. Releasing them here rather than from a separate handler keeps
+	 * the ordering against the I2C write explicit.
+	 */
+	if (rk808->power_hold_gpios) {
+		unsigned int i;
+
+		for (i = 0; i < rk808->power_hold_gpios->ndescs; i++)
+			gpiod_set_value_cansleep(rk808->power_hold_gpios->desc[i], 0);
+
+		msleep(rk808->power_hold_delay_ms);
+	}
+
 	ret = regmap_update_bits(rk808->regmap, reg, bit, bit);
 	if (ret)
 		dev_err(rk808->dev, "Failed to shutdown device!\n");
@@ -874,6 +894,15 @@ int rk8xx_probe(struct device *dev, int variant, unsigned int irq, struct regmap
 
 	if (device_property_read_bool(dev, "system-power-controller") ||
 	    device_property_read_bool(dev, "rockchip,system-power-controller")) {
+		rk808->power_hold_gpios = devm_gpiod_get_array_optional(dev,
+							"power-hold", GPIOD_OUT_HIGH);
+		if (IS_ERR(rk808->power_hold_gpios))
+			return dev_err_probe(dev, PTR_ERR(rk808->power_hold_gpios),
+					     "failed to get power hold GPIOs\n");
+
+		device_property_read_u32(dev, "power-hold-delay-ms",
+					 &rk808->power_hold_delay_ms);
+
 		ret = devm_register_sys_off_handler(dev,
 				    SYS_OFF_MODE_POWER_OFF_PREPARE, SYS_OFF_PRIO_HIGH,
 				    &rk808_power_off, rk808);
diff --git a/include/linux/mfd/rk808.h b/include/linux/mfd/rk808.h
index 7ffc904..eda111e 100644
--- a/include/linux/mfd/rk808.h
+++ b/include/linux/mfd/rk808.h
@@ -1459,6 +1459,8 @@ enum {
 	RK818_ID = 0x8180,
 };
 
+struct gpio_descs;
+
 struct rk808 {
 	struct device			*dev;
 	struct regmap_irq_chip_data	*irq_data;
@@ -1466,6 +1468,8 @@ struct rk808 {
 	long				variant;
 	const struct regmap_config	*regmap_cfg;
 	const struct regmap_irq_chip	*regmap_irq_chip;
+	struct gpio_descs		*power_hold_gpios;
+	u32				power_hold_delay_ms;
 };
 
 void rk8xx_shutdown(struct device *dev);
-- 
2.55.0.windows.3

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

[Yaozhong Li]

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 and GPIO1_B5 low during shutdown, before
writing the RK808's shutdown bit. Mainline does not describe GPIO1_D0 at
all, and describes GPIO1_B5 as the backlight enable GPIO - the vendor's
own backlight node has no enable GPIO. Nothing therefore releases either
line at power-off, and while the backlight owns GPIO1_B5 it can hold it
asserted, which is enough to make the board come back up on its own.

Describe both lines in the PMIC node and drop the backlight enable-gpios,
with the settle time the vendor uses.

Fixes: 171582e00db1 ("arm64: dts: rockchip: add support for firefly-rk3399 board")
Signed-off-by: Yaozhong Li <yaozhonguwl@gmail.com>
---
 arch/arm64/boot/dts/rockchip/rk3399-firefly.dts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts b/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
index 0568dfa..75b75fe 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3399-firefly.dts
@@ -27,7 +27,6 @@ chosen {
 
 	backlight: backlight {
 		compatible = "pwm-backlight";
-		enable-gpios = <&gpio1 RK_PB5 GPIO_ACTIVE_HIGH>;
 		pwms = <&pwm0 0 25000 0>;
 		brightness-levels = <
 			  0   1   2   3   4   5   6   7
@@ -327,6 +326,9 @@ rk808: pmic@1b {
 		pinctrl-names = "default";
 		pinctrl-0 = <&pmic_int_l>;
 		system-power-controller;
+		power-hold-gpios = <&gpio1 RK_PD0 GPIO_ACTIVE_HIGH>,
+				   <&gpio1 RK_PB5 GPIO_ACTIVE_HIGH>;
+		power-hold-delay-ms = <200>;
 		wakeup-source;
 
 		vcc1-supply = <&vcc_sys>;
-- 
2.55.0.windows.3