mmc/SD-card initialization may fail on NanoPi R4S with
"mmc1: problem reading SD Status register" /
"mmc1: error -110 whilst initialising SD card"
either on cold boot or after a reboot.
Moreover, the system would also sometimes hang upon reboot.
This is caused by vcc3v0-sd's "regulator-always-on", which triggers
an erroneous double-initialization of the regulator. This causes
voltage fluctuations that can, depending on timing, prevent the
SD card from initializing correctly.
Adding some liberal delay via "off-on-delay-us" is ineffective since
that codepath is skipped as long "regulator-always-on" is set.
Removing "regulator-always-on" alone is not sufficient because that
would allow the system to set GPIO0_A1 to LOW upon reboot, which may
cause the system to hang.
In order to allow the system to set GPIO0_A1 to HIGH upon initialization
but prevent it from changing it back to LOW, this patch increases the
usage count of vcc3v0-sd from 1 to 2, whereas the additional reference,
"vcc1v8_s3", is marked as "always-on", causing permanent retention.
Signed-off-by: Christian Kohlschütter <christian@xxxxxxxxxxxxxxxx>
---
arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi
index 8c0ff6c96e03..38507a6e3046 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi
@@ -61,7 +61,17 @@ vcc1v8_s3: vcc1v8-s3 {
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-name = "vcc1v8_s3";
- vin-supply = <&vcc_1v8>;
+
+ /*
+ * Workaround to skip setting gpio0 RK_PA1 to LOW upon reboot,
+ * which may freeze the system.
+ *
+ * Adding a reference to vcc3v0_sd increases its num_users
+ * count to 2, preventing deactivation since this regulator is
+ * marked "always-on".
+ */
+ // vin-supply = <&vcc_1v8>; // actual supply
+ vin-supply = <&vcc3v0_sd>;
};
vcc3v0_sd: vcc3v0-sd {
@@ -70,7 +80,6 @@ vcc3v0_sd: vcc3v0-sd {
gpio = <&gpio0 RK_PA1 GPIO_ACTIVE_HIGH>;
pinctrl-names = "default";
pinctrl-0 = <&sdmmc0_pwr_h>;
- regulator-always-on;
regulator-min-microvolt = <3000000>;
regulator-max-microvolt = <3000000>;
regulator-name = "vcc3v0_sd";
--
2.36.1
