The digital side of the Black Level Calibration (BLC) function must be
disabled when generating a test pattern to avoid artifacts in the image.
The driver disables BLC correctly at the hardware level, but the feature
gets reenabled by v4l2_ctrl_handler_setup() the next time the device is
powered on.
Fix this by marking the BLC controls as inactive when generating a test
pattern, and ignoring control set requests on inactive controls.
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
drivers/media/i2c/mt9p031.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
index 33daace..9102b23 100644
--- a/drivers/media/i2c/mt9p031.c
+++ b/drivers/media/i2c/mt9p031.c
@@ -655,6 +655,9 @@ static int mt9p031_s_ctrl(struct v4l2_ctrl *ctrl)
u16 data;
int ret;
+ if (ctrl->flags & V4L2_CTRL_FLAG_INACTIVE)
+ return 0;
+
switch (ctrl->id) {
case V4L2_CID_EXPOSURE:
ret = mt9p031_write(client, MT9P031_SHUTTER_WIDTH_UPPER,
@@ -709,8 +712,16 @@ static int mt9p031_s_ctrl(struct v4l2_ctrl *ctrl)
MT9P031_READ_MODE_2_ROW_MIR, 0);
case V4L2_CID_TEST_PATTERN:
+ /* The digital side of the Black Level Calibration function must
+ * be disabled when generating a test pattern to avoid artifacts
+ * in the image. Activate (deactivate) the BLC-related controls
+ * when the test pattern is enabled (disabled).
+ */
+ v4l2_ctrl_activate(mt9p031->blc_auto, ctrl->val == 0);
+ v4l2_ctrl_activate(mt9p031->blc_offset, ctrl->val == 0);
+
if (!ctrl->val) {
- /* Restore the black level compensation settings. */
+ /* Restore the BLC settings. */
if (mt9p031->blc_auto->cur.val != 0) {
ret = mt9p031_s_ctrl(mt9p031->blc_auto);
if (ret < 0)
@@ -735,9 +746,7 @@ static int mt9p031_s_ctrl(struct v4l2_ctrl *ctrl)
if (ret < 0)
return ret;
- /* Disable digital black level compensation when using a test
- * pattern.
- */
+ /* Disable digital BLC when generating a test pattern. */
ret = mt9p031_set_mode2(mt9p031, MT9P031_READ_MODE_2_ROW_BLC,
0);
if (ret < 0)
--
Regards,
Laurent Pinchart
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