The documentation states that the BNR factor is a multiplier coded as
u3.13 and with a range of (0, 8). This is not correct, as the isp is
adding 1.0 to the gain applied, ie Pout = { Pin * (1 + Gx) }.
It means that a gain of 1.0 should be coded as 0.
Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@xxxxxxxxxxxxxxxx>
---
drivers/staging/media/ipu3/include/uapi/intel-ipu3.h | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h
index dbdd015ce220..caa358e0bae4 100644
--- a/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h
+++ b/drivers/staging/media/ipu3/include/uapi/intel-ipu3.h
@@ -626,8 +626,11 @@ struct ipu3_uapi_stats_3a {
* @b: white balance gain for B channel.
* @gb: white balance gain for Gb channel.
*
- * Precision u3.13, range [0, 8). White balance correction is done by applying
- * a multiplicative gain to each color channels prior to BNR.
+ * For BNR parameters WB gain factor for the three channels [Ggr, Ggb, Gb, Gr].
+ * Their precision is U3.13 and the range is (0, 8) and the actual gain is
+ * Gx + 1, it is typically Gx = 1.
+ *
+ * Pout = {Pin * (1 + Gx)}.
*/
struct ipu3_uapi_bnr_static_config_wb_gains_config {
__u16 gr;
--
2.34.1
