regulator: s5m8767: do not use reset value as DVS voltage if GPIO DVS is disabled

The driver and its bindings, before commit 04f9f068 ("regulator:
s5m8767: Modify parsing method of the voltage table of buck2/3/4") were
requiring to provide at least one safe/default voltage for DVS registers
if DVS GPIO is not being enabled.

IOW, if s5m8767,pmic-buck2-uses-gpio-dvs is missing, the
s5m8767,pmic-buck2-dvs-voltage should still be present and contain one
voltage.

This requirement was coming from driver behavior matching this condition
(none of DVS GPIO is enabled): it was always initializing the DVS
selector pins to 0 and keeping the DVS enable setting at reset value
(enabled).  Therefore if none of DVS GPIO is enabled in devicetree,
driver was configuring the first DVS voltage for buck[234].

Mentioned commit 04f9f068 ("regulator: s5m8767: Modify parsing
method of the voltage table of buck2/3/4") broke it because DVS voltage
won't be parsed from devicetree if DVS GPIO is not enabled.  After the
change, driver will configure bucks to use the register reset value as
voltage which might have unpleasant effects.

Fix this by relaxing the bindings constrain: if DVS GPIO is not enabled
in devicetree (therefore DVS voltage is also not parsed), explicitly
disable it.

Cc: <stable@vger.kernel.org>
Fixes: 04f9f068 ("regulator: s5m8767: Modify parsing method of the voltage table of buck2/3/4")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Rob Herring <robh@kernel.org>
Message-Id: <20211008113723.134648-2-krzysztof.kozlowski@canonical.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/samsung,s5m8767.txt

@@ -13,6 +13,14 @@ common regulator binding documented in:
 
 
 Required properties of the main device node (the parent!):
+ - s5m8767,pmic-buck-ds-gpios: GPIO specifiers for three host gpio's used
+   for selecting GPIO DVS lines. It is one-to-one mapped to dvs gpio lines.
+
+ [1] If either of the 's5m8767,pmic-buck[2/3/4]-uses-gpio-dvs' optional
+     property is specified, then all the eight voltage values for the
+     's5m8767,pmic-buck[2/3/4]-dvs-voltage' should be specified.
+
+Optional properties of the main device node (the parent!):
  - s5m8767,pmic-buck2-dvs-voltage: A set of 8 voltage values in micro-volt (uV)
    units for buck2 when changing voltage using gpio dvs. Refer to [1] below
    for additional information.
@@ -25,19 +33,6 @@ Required properties of the main device node (the parent!):
    units for buck4 when changing voltage using gpio dvs. Refer to [1] below
    for additional information.
 
- - s5m8767,pmic-buck-ds-gpios: GPIO specifiers for three host gpio's used
-   for selecting GPIO DVS lines. It is one-to-one mapped to dvs gpio lines.
-
- [1] If none of the 's5m8767,pmic-buck[2/3/4]-uses-gpio-dvs' optional
-     property is specified, the 's5m8767,pmic-buck[2/3/4]-dvs-voltage'
-     property should specify atleast one voltage level (which would be a
-     safe operating voltage).
-
-     If either of the 's5m8767,pmic-buck[2/3/4]-uses-gpio-dvs' optional
-     property is specified, then all the eight voltage values for the
-     's5m8767,pmic-buck[2/3/4]-dvs-voltage' should be specified.
-
-Optional properties of the main device node (the parent!):
  - s5m8767,pmic-buck2-uses-gpio-dvs: 'buck2' can be controlled by gpio dvs.
  - s5m8767,pmic-buck3-uses-gpio-dvs: 'buck3' can be controlled by gpio dvs.
  - s5m8767,pmic-buck4-uses-gpio-dvs: 'buck4' can be controlled by gpio dvs.

drivers/regulator/s5m8767.c

@@ -850,18 +850,15 @@ static int s5m8767_pmic_probe(struct platform_device *pdev)
 	/* DS4 GPIO */
 	gpio_direction_output(pdata->buck_ds[2], 0x0);
 
-	if (pdata->buck2_gpiodvs || pdata->buck3_gpiodvs ||
-	   pdata->buck4_gpiodvs) {
-		regmap_update_bits(s5m8767->iodev->regmap_pmic,
-				S5M8767_REG_BUCK2CTRL, 1 << 1,
-				(pdata->buck2_gpiodvs) ? (1 << 1) : (0 << 1));
-		regmap_update_bits(s5m8767->iodev->regmap_pmic,
-				S5M8767_REG_BUCK3CTRL, 1 << 1,
-				(pdata->buck3_gpiodvs) ? (1 << 1) : (0 << 1));
-		regmap_update_bits(s5m8767->iodev->regmap_pmic,
-				S5M8767_REG_BUCK4CTRL, 1 << 1,
-				(pdata->buck4_gpiodvs) ? (1 << 1) : (0 << 1));
-	}
+	regmap_update_bits(s5m8767->iodev->regmap_pmic,
+			   S5M8767_REG_BUCK2CTRL, 1 << 1,
+			   (pdata->buck2_gpiodvs) ? (1 << 1) : (0 << 1));
+	regmap_update_bits(s5m8767->iodev->regmap_pmic,
+			   S5M8767_REG_BUCK3CTRL, 1 << 1,
+			   (pdata->buck3_gpiodvs) ? (1 << 1) : (0 << 1));
+	regmap_update_bits(s5m8767->iodev->regmap_pmic,
+			   S5M8767_REG_BUCK4CTRL, 1 << 1,
+			   (pdata->buck4_gpiodvs) ? (1 << 1) : (0 << 1));
 
 	/* Initialize GPIO DVS registers */
 	for (i = 0; i < 8; i++) {