Hi Laurent,
The patch is correct, but I noticed a pre-existing bug that should be
fixed. See below.
On 05/07/14 17:40, Laurent Pinchart wrote:
> 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);
This doesn't do what you expect. What you want is to set the blc_auto
control to the current value, but mt9p031_s_ctrl(mt9p031->blc_auto) will
set it to the *new* value, which may not be the same. Ditto for doing the
same for blc_offset.
It's best to just call mt9p031_write directly, rather than going through
mt9p031_s_ctrl.
Regards,
Hans
> 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)
>
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
