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media: usbtv: fix brightness and contrast controls

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Because the brightness and contrast controls share a register,
usbtv_s_ctrl needs to read the existing values for both controls before
inserting the new value. However, the code accidentally wrote to the
registers (from an uninitialised stack array), rather than reading them.

The user-visible effect of this was that adjusting the brightness would
also set the contrast to a random value, and vice versa -- so it wasn't
possible to correctly adjust the brightness of usbtv's video output.

Tested with an "EasyDAY" UTV007 device.

Fixes: c53a846c48 ("usbtv: add video controls")

Signed-off-by: Adam Sampson <ats@offog.org>
Reviewed-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Adam Sampson 2017-10-24 16:14:46 -04:00 committed by Mauro Carvalho Chehab
parent 74ee047751
commit b3168c87c0
1 changed files with 2 additions and 2 deletions
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4
drivers/media/usb/usbtv/usbtv-video.c
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@ -718,8 +718,8 @@ static int usbtv_s_ctrl(struct v4l2_ctrl *ctrl)
*/
if (ctrl->id == V4L2_CID_BRIGHTNESS || ctrl->id == V4L2_CID_CONTRAST) {
ret = usb_control_msg(usbtv->udev,
usb_sndctrlpipe(usbtv->udev, 0), USBTV_CONTROL_REG,
USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
usb_rcvctrlpipe(usbtv->udev, 0), USBTV_CONTROL_REG,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0, USBTV_BASE + 0x0244, (void *)data, 3, 0);
if (ret < 0)
goto error;