Hi Philipp,
Thank you for the patch.
On Friday 14 Jul 2017 22:14:22 Philipp Zabel wrote:
> Some USB webcam controllers have extension unit controls that report
> different lengths via GET_LEN, depending on internal state.
If I ever need to hire a hardware designer, I'll make sure to reject any
candidate who thinks that creativity is an asset :-(
If the size changes, could the flags change as well ? Should you issue a
GET_INFO too ?
> Add a flag to mark these controls as variable length and issue GET_LEN
> before GET/SET_CUR transfers to verify the current length.
What happens if the internal state changes between the GET_LEN and the
GET/SET_CUR ?
> Signed-off-by: Philipp Zabel <philipp.zabel@xxxxxxxxx>
> ---
> drivers/media/usb/uvc/uvc_ctrl.c | 26 +++++++++++++++++++++++++-
> include/uapi/linux/uvcvideo.h | 2 ++
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c
> b/drivers/media/usb/uvc/uvc_ctrl.c index c2ee6e39fd0c..ce69e2c6937d 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -1597,7 +1597,7 @@ static void uvc_ctrl_fixup_xu_info(struct uvc_device
> *dev, struct usb_device_id id;
> u8 entity;
> u8 selector;
> - u8 flags;
> + u16 flags;
> };
>
> static const struct uvc_ctrl_fixup fixups[] = {
> @@ -1799,6 +1799,30 @@ int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
> goto done;
> }
>
> + if ((ctrl->info.flags & UVC_CTRL_FLAG_VARIABLE_LEN) && reqflags) {
> + data = kmalloc(2, GFP_KERNEL);
> + /* Check if the control length has changed */
> + ret = uvc_query_ctrl(chain->dev, UVC_GET_LEN, xqry->unit,
> + chain->dev->intfnum, xqry->selector,
data,
> + 2);
> + size = le16_to_cpup((__le16 *)data);
> + kfree(data);
Now data is not NULL.
> + if (ret < 0) {
> + uvc_trace(UVC_TRACE_CONTROL,
> + "GET_LEN failed on control %pUl/%u (%d).\n",
> + entity->extension.guidExtensionCode,
> + xqry->selector, ret);
> + goto done;
And the kfree(data) at the done label will cause a double free.
> + }
> + if (ctrl->info.size != size) {
> + uvc_trace(UVC_TRACE_CONTROL,
> + "XU control %pUl/%u queried: len %u ->
%u\n",
> + entity->extension.guidExtensionCode,
> + xqry->selector, ctrl->info.size, size);
> + ctrl->info.size = size;
> + }
> + }
How about moving this code (or part of it at least) to a function that could
be shared with uvc_ctrl_fill_xu_info() ?
> if (size != xqry->size) {
> ret = -ENOBUFS;
> goto done;
> diff --git a/include/uapi/linux/uvcvideo.h b/include/uapi/linux/uvcvideo.h
> index 3b081862b9e8..0f0d63e79045 100644
> --- a/include/uapi/linux/uvcvideo.h
> +++ b/include/uapi/linux/uvcvideo.h
> @@ -27,6 +27,8 @@
> #define UVC_CTRL_FLAG_RESTORE (1 << 6)
> /* Control can be updated by the camera. */
> #define UVC_CTRL_FLAG_AUTO_UPDATE (1 << 7)
> +/* Control can change LEN */
> +#define UVC_CTRL_FLAG_VARIABLE_LEN (1 << 8)
>
> #define UVC_CTRL_FLAG_GET_RANGE \
> (UVC_CTRL_FLAG_GET_CUR | UVC_CTRL_FLAG_GET_MIN | \
--
Regards,
Laurent Pinchart
