media: i2c: adv7180: fix reserved bit in Video Selection 2

This bit is marked as reserved in the ADV Hardware Reference Manual.

Resetting this bit seems to cause increased video noise. Setting this
bit according to the Hardware Reference Manual reduces the video noise
immediately.

Signed-off-by: Benjamin Marty <info@benjaminmarty.ch>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Tested-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

diff --git a/drivers/media/i2c/adv7180.c b/drivers/media/i2c/adv7180.c
index e3a57c1..5fde524 100644 (file)
--- a/drivers/media/i2c/adv7180.c
+++ b/drivers/media/i2c/adv7180.c
@@ -43,6 +43,7 @@
 #define ADV7180_INPUT_CONTROL_INSEL_MASK               0x0f
 
 #define ADV7182_REG_INPUT_VIDSEL                       0x0002
+#define ADV7182_REG_INPUT_RESERVED                     BIT(2)
 
 #define ADV7180_REG_OUTPUT_CONTROL                     0x0003
 #define ADV7180_REG_EXTENDED_OUTPUT_CONTROL            0x0004
@@ -1060,7 +1061,9 @@ static int adv7182_init(struct adv7180_state *state)
 
 static int adv7182_set_std(struct adv7180_state *state, unsigned int std)
 {
-       return adv7180_write(state, ADV7182_REG_INPUT_VIDSEL, std << 4);
+       /* Failing to set the reserved bit can result in increased video noise */
+       return adv7180_write(state, ADV7182_REG_INPUT_VIDSEL,
+                            (std << 4) | ADV7182_REG_INPUT_RESERVED);
 }
 
 enum adv7182_input_type {