[PATCH] media: usbtv: fix brightness and contrast controls

[PATCH] media: usbtv: fix brightness and contrast controls

[Adam Sampson]

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: c53a846c48f2 ("usbtv: add video controls")
Signed-off-by: Adam Sampson <ats@offog.org>
---
 drivers/media/usb/usbtv/usbtv-video.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/usb/usbtv/usbtv-video.c b/drivers/media/usb/usbtv/usbtv-video.c
index 95b5f43..3668a04 100644
--- a/drivers/media/usb/usbtv/usbtv-video.c
+++ b/drivers/media/usb/usbtv/usbtv-video.c
@@ -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;
-- 
2.1.4

Re: [PATCH] media: usbtv: fix brightness and contrast controls

[Lubomir Rintel]

On Tue, 2017-10-24 at 21:14 +0100, Adam Sampson wrote:
> 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: c53a846c48f2 ("usbtv: add video controls")
> Signed-off-by: Adam Sampson <ats@offog.org>

Thank you!

Reviewed-By: Lubomir Rintel <lkundrak@v3.sk>

> ---
>  drivers/media/usb/usbtv/usbtv-video.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/usb/usbtv/usbtv-video.c
> b/drivers/media/usb/usbtv/usbtv-video.c
> index 95b5f43..3668a04 100644
> --- a/drivers/media/usb/usbtv/usbtv-video.c
> +++ b/drivers/media/usb/usbtv/usbtv-video.c
> @@ -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;