On Tue, Jun 30, 2020 at 11:10:51AM +1000, Anand K Mistry wrote:

Without a of_map_mode implementation, the regulator-allowed-modes
devicetree field is skipped, and attempting to change the regulator mode
results in an error:
[    1.439165] vpca15: mode operation not allowed

The modes aren't documented in the binding document, any new device tree
property needs to be added to the binding document.

+static unsigned int mt6397_map_mode(unsigned int mode)
+{
+	return mode == MT6397_BUCK_MODE_AUTO ?
+		REGULATOR_MODE_NORMAL : REGULATOR_MODE_FAST;
+}
+

Please write normal conditional statements to improve legibility, the
ternery operator has uses but they're pretty specialist.