media: ov8856: apply digital gain by setting global gain control register

MWB gain register are used to set gain for each mwb channel mannually.
However, it will involve some artifacts if gain cannot be applied to
each channel synchronously. Enable global gain control to set digital
global gain instead of setting AWB gain separately to fix this issue.
Signed-off-by: Bingbu Cao <bingbu.cao@intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/i2c/ov8856.c

@@ -63,6 +63,7 @@
 #define	OV8856_ANAL_GAIN_STEP		1
 
 /* Digital gain controls from sensor */
+#define OV8856_REG_DIGITAL_GAIN		0x350a
 #define OV8856_REG_MWB_R_GAIN		0x5019
 #define OV8856_REG_MWB_G_GAIN		0x501b
 #define OV8856_REG_MWB_B_GAIN		0x501d
@@ -351,7 +352,7 @@ static const struct ov8856_reg lane_2_mode_3280x2464[] = {
 		{0x484b, 0x05},
 		{0x5000, 0x57},
 		{0x5001, 0x0a},
-		{0x5004, 0x04},
+		{0x5004, 0x06},
 		{0x502e, 0x03},
 		{0x5030, 0x41},
 		{0x5795, 0x02},
@@ -543,7 +544,7 @@ static const struct ov8856_reg lane_2_mode_1640x1232[] = {
 		{0x484b, 0x05},
 		{0x5000, 0x57},
 		{0x5001, 0x0a},
-		{0x5004, 0x04},
+		{0x5004, 0x06},
 		{0x502e, 0x03},
 		{0x5030, 0x41},
 		{0x5795, 0x00},
@@ -734,7 +735,7 @@ static const struct ov8856_reg lane_4_mode_3280x2464[] = {
 		{0x484b, 0x05},
 		{0x5000, 0x57},
 		{0x5001, 0x0a},
-		{0x5004, 0x04},
+		{0x5004, 0x06},
 		{0x502e, 0x03},
 		{0x5030, 0x41},
 		{0x5780, 0x14},
@@ -925,7 +926,7 @@ static const struct ov8856_reg lane_4_mode_1640x1232[] = {
 		{0x484b, 0x05},
 		{0x5000, 0x57},
 		{0x5001, 0x0a},
-		{0x5004, 0x04},
+		{0x5004, 0x06},
 		{0x502e, 0x03},
 		{0x5030, 0x41},
 		{0x5780, 0x14},
@@ -1755,19 +1756,7 @@ static int ov8856_identify_module(struct ov8856 *ov8856)
 
 static int ov8856_update_digital_gain(struct ov8856 *ov8856, u32 d_gain)
 {
-	int ret;
-
-	ret = ov8856_write_reg(ov8856, OV8856_REG_MWB_R_GAIN,
-			       OV8856_REG_VALUE_16BIT, d_gain);
-	if (ret)
-		return ret;
-
-	ret = ov8856_write_reg(ov8856, OV8856_REG_MWB_G_GAIN,
-			       OV8856_REG_VALUE_16BIT, d_gain);
-	if (ret)
-		return ret;
-
-	return ov8856_write_reg(ov8856, OV8856_REG_MWB_B_GAIN,
+	return ov8856_write_reg(ov8856, OV8856_REG_DIGITAL_GAIN,
 				OV8856_REG_VALUE_16BIT, d_gain);
 }