According to ov2640 software application notes, there are two Automatic
White Balance (AWB) modes, which are selected by DSP register 0xc7:
1) Simple AWB: assumes the average color is gray
+ independent from lens
- doesn't work well if captured area contains unbalanced colors
(e.g. large blue background)
2) Advanced AWB: uses color temperature information
+ more accurate, works with all image contents
- lens specific, requires calibration
Signed-off-by: Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx>
---
drivers/media/i2c/ov2640.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/media/i2c/ov2640.c b/drivers/media/i2c/ov2640.c
index fd1b215b6dec..11f1b807c292 100644
--- a/drivers/media/i2c/ov2640.c
+++ b/drivers/media/i2c/ov2640.c
@@ -106,6 +106,10 @@
#define CTRL1_AWB_GAIN 0x04
#define CTRL1_LENC 0x02
#define CTRL1_PRE 0x01
+/* REG 0xC7 (unknown name): affects Auto White Balance (AWB)
+ * AWB_OFF 0x40
+ * AWB_SIMPLE 0x10
+ * AWB_ON 0x00 (Advanced AWB ?) */
#define R_DVP_SP 0xD3 /* DVP output speed control */
#define R_DVP_SP_AUTO_MODE 0x80
#define R_DVP_SP_DVP_MASK 0x3F /* DVP PCLK = sysclk (48)/[6:0] (YUV0);
@@ -449,7 +453,7 @@ static const struct regval_list ov2640_init_regs[] = {
{ 0xc5, 0x11 },
{ 0xc6, 0x51 },
{ 0xbf, 0x80 },
- { 0xc7, 0x10 },
+ { 0xc7, 0x10 }, /* simple AWB */
{ 0xb6, 0x66 },
{ 0xb8, 0xA5 },
{ 0xb7, 0x64 },
--
2.12.2
