[media] mt9p031: Really disable Black Level Calibration in test pattern mode

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@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

diff --git a/drivers/media/i2c/mt9p031.c b/drivers/media/i2c/mt9p031.c
index 33daace..9102b23 100644 (file)
--- 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)