media: i2c: adv7180: fix adv7280 BT.656-4 compatibility

Captured video would be out of sync when using the adv7280 with
the BT.656-4 protocol. Certain registers (0x04, 0x31, 0xE6) had to
be configured properly to ensure BT.656-4 compatibility.

An error in the adv7280 reference manual suggested that EAV/SAV mode
was enabled by default, however upon inspecting register 0x31, it was
determined to be disabled by default.

[fabio: Introduce "adv,force-bt656-4" to not affect the existing users]
[hverkuil: fix a small checkpatch alignment warning]

Signed-off-by: Matthew Michilot <[e-mail]>
Reviewed-by: Tim Harvey <[e-mail]>
Signed-off-by: Fabio Estevam <[e-mail]>
Tested-by: Tim Harvey <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/i2c/adv7180.c

···
 #define ADV7180_REG_SHAP_FILTER_CTL_1	0x0017
 #define ADV7180_REG_CTRL_2		0x001d
 #define ADV7180_REG_VSYNC_FIELD_CTL_1	0x0031
+#define ADV7180_VSYNC_FIELD_CTL_1_NEWAV 0x12
 #define ADV7180_REG_MANUAL_WIN_CTL_1	0x003d
 #define ADV7180_REG_MANUAL_WIN_CTL_2	0x003e
 #define ADV7180_REG_MANUAL_WIN_CTL_3	0x003f
···
 	struct i2c_client	*vpp_client;
 	const struct adv7180_chip_info *chip_info;
 	enum v4l2_field		field;
+	bool			force_bt656_4;
 };
 #define to_adv7180_sd(_ctrl) (&container_of(_ctrl->handler,		\
 					    struct adv7180_state,	\
···
 		adv7180_write(state, ADV7180_REG_EXTENDED_OUTPUT_CONTROL, 0x57);
 		adv7180_write(state, ADV7180_REG_CTRL_2, 0xc0);
 	} else {
-		if (state->chip_info->flags & ADV7180_FLAG_V2)
-			adv7180_write(state,
-				      ADV7180_REG_EXTENDED_OUTPUT_CONTROL,
-				      0x17);
+		if (state->chip_info->flags & ADV7180_FLAG_V2) {
+			if (state->force_bt656_4) {
+				/* ITU-R BT.656-4 compatible */
+				adv7180_write(state,
+					      ADV7180_REG_EXTENDED_OUTPUT_CONTROL,
+					      ADV7180_EXTENDED_OUTPUT_CONTROL_NTSCDIS);
+				/* Manually set NEWAVMODE */
+				adv7180_write(state,
+					      ADV7180_REG_VSYNC_FIELD_CTL_1,
+					      ADV7180_VSYNC_FIELD_CTL_1_NEWAV);
+				/* Manually set V bit end position in NTSC mode */
+				adv7180_write(state,
+					      ADV7180_REG_NTSC_V_BIT_END,
+					      ADV7180_NTSC_V_BIT_END_MANUAL_NVEND);
+			} else {
+				adv7180_write(state,
+					      ADV7180_REG_EXTENDED_OUTPUT_CONTROL,
+					      0x17);
+			}
+		}
 		else
 			adv7180_write(state,
 				      ADV7180_REG_EXTENDED_OUTPUT_CONTROL,
···
 static int adv7180_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
+	struct device_node *np = client->dev.of_node;
 	struct adv7180_state *state;
 	struct v4l2_subdev *sd;
 	int ret;
···
 		v4l_err(client, "request for reset pin failed: %d\n", ret);
 		return ret;
 	}
+
+	if (of_property_read_bool(np, "adv,force-bt656-4"))
+		state->force_bt656_4 = true;
 
 	if (state->chip_info->flags & ADV7180_FLAG_MIPI_CSI2) {
 		state->csi_client = i2c_new_dummy_device(client->adapter,