regulator: pca9450: Clear PRESET_EN bit to fix BUCK1/2/3 voltage setting

The driver uses the DVS registers PCA9450_REG_BUCKxOUT_DVS0 to set the
voltage for the buck regulators 1, 2 and 3. This has no effect as the
PRESET_EN bit is set by default and therefore the preset values are used
instead, which are set to 850 mV.

To fix this we clear the PRESET_EN bit at time of initialization.

Fixes: 0935ff5f ("regulator: pca9450: add pca9450 pmic driver")
Cc: <stable@vger.kernel.org>
Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Link: https://lore.kernel.org/r/20210222115229.166620-1-frieder.schrempf@kontron.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/pca9450-regulator.c

@@ -797,6 +797,14 @@ static int pca9450_i2c_probe(struct i2c_client *i2c,
 		return ret;
 	}
 
+	/* Clear PRESET_EN bit in BUCK123_DVS to use DVS registers */
+	ret = regmap_clear_bits(pca9450->regmap, PCA9450_REG_BUCK123_DVS,
+				BUCK123_PRESET_EN);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to clear PRESET_EN bit: %d\n", ret);
+		return ret;
+	}
+
 	/* Set reset behavior on assertion of WDOG_B signal */
 	ret = regmap_update_bits(pca9450->regmap, PCA9450_REG_RESET_CTRL,
 				WDOG_B_CFG_MASK, WDOG_B_CFG_COLD_LDO12);

include/linux/regulator/pca9450.h

@@ -147,6 +147,9 @@ enum {
 #define BUCK6_FPWM			0x04
 #define BUCK6_ENMODE_MASK		0x03
 
+/* PCA9450_REG_BUCK123_PRESET_EN bit */
+#define BUCK123_PRESET_EN		0x80
+
 /* PCA9450_BUCK1OUT_DVS0 bits */
 #define BUCK1OUT_DVS0_MASK		0x7F
 #define BUCK1OUT_DVS0_DEFAULT		0x14