[PATCH v3 19/23] media: atmel: atmel-isc-base: clamp wb gain coefficients

Eugen Hristev
2021-12-13T13:55:46Z

White balance computed gains can overflow above the 13 bits hardware
coefficient that can be used, in some specific scenarios like a subexposure
from the sensor when the image is mostly black.
In this case the computed gain has to be clamped to the maximum value
allowed by the hardware.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
drivers/media/platform/atmel/atmel-isc-base.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
index f1f1019f9d82..31c8e3029eee 100644
--- a/drivers/media/platform/atmel/atmel-isc-base.c
+++ b/drivers/media/platform/atmel/atmel-isc-base.c
@@ -1415,6 +1415,10 @@ static void isc_wb_update(struct isc_ctrls *ctrls)
/* multiply both gains and adjust for decimals */
ctrls->gain[c] = s_gain[c] * gw_gain[c];
ctrls->gain[c] >>= 9;
+
+ /* make sure we are not out of range */
+ ctrls->gain[c] = clamp_val(ctrls->gain[c], 0, GENMASK(12, 0));
+
v4l2_dbg(1, debug, &isc->v4l2_dev,
"isc wb: component %d, final gain %u\n",
c, ctrls->gain[c]);
--
2.25.1