media: atmel: atmel-isc-base: clamp wb gain coefficients

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>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
index d92ffc07418f2ed869d620b90fe7879245e6a867..db15770d5b88b2f5895a608f0483810e20c1eef0 100644 (file)
--- a/drivers/media/platform/atmel/atmel-isc-base.c
+++ b/drivers/media/platform/atmel/atmel-isc-base.c
@@ -1375,6 +1375,10 @@ 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]);