arm64: dts: imx8mp-kontron: Fix boot order for PMIC and RTC

The PMIC provides a level-shifter for the I2C lines to the RTC. As the
level shifter needs to be enabled before the RTC can be accessed, make sure
that the PMIC driver is probed first.

As the PMIC also provides the supply voltage for the RTC through the 3.3V
regulator, simply express this in the DT to create the required dependency.

Avoid sporadic boot hangs that occurred when the RTC was accessed before
the level-shifter was enabled.

Fixes: 946ab10e3f40f ("arm64: dts: Add support for Kontron OSM-S i.MX8MP SoM and BL carrier board")
Signed-off-by: Annette Kobou <annette.kobou@kontron.de>
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Frank Li <Frank.Li@nxp.com>

diff --git a/arch/arm64/boot/dts/freescale/imx8mp-kontron-osm-s.dtsi b/arch/arm64/boot/dts/freescale/imx8mp-kontron-osm-s.dtsi
index b97bfeb1c30f89610ee6cfcb0440a409c91dc25f..bc1a261bb000ed0e8071d214111c12689bc394d0 100644 (file)
--- a/arch/arm64/boot/dts/freescale/imx8mp-kontron-osm-s.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mp-kontron-osm-s.dtsi
@@ -330,6 +330,12 @@
                pinctrl-names = "default";
                pinctrl-0 = <&pinctrl_rtc>;
                interrupts-extended = <&gpio3 24 IRQ_TYPE_LEVEL_LOW>;
+               /*
+                * While specifying the vdd-supply is normally not strictly necessary,
+                * here it also makes sure that the PMIC driver enables the level-
+                * shifter for the RTC before the RTC is probed.
+                */
+               vdd-supply = <&reg_vdd_3v3>;
        };
 };