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[media] ov2640: add information about DSP register 0xc7
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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@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
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Frank Schaefer authored and Mauro Carvalho Chehab committed Apr 19, 2017
1 parent d81638e commit 06dd8f7
Showing 1 changed file with 5 additions and 1 deletion.
6 changes: 5 additions & 1 deletion drivers/media/i2c/ov2640.c
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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 },
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