Arch Linux

Description: no exposure setting on webcams using uvcvideo


Additional info:
* package version(s) 4.17.2-1


Steps to reproduce:
a small amount of the buffer was added to the commit https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?h=linux-4.17.y&id=859086ae3636eae0bf9f0fbbce2daf4d41ae9474 in the function description uvc_ctrl_get_flags (data = kmalloc (1, GFP_KERNEL); and ret = uvc_query_ctrl (dev, UVC_GET_INFO, ctrl-> entity-> id, dev-> intfnum, info-> selector, data, 1);) and it turned out that when reassigning variable ret through the specified function in function uvc_ctrl_fill_xu_info the size did not suffice what to contain exposition settings as I think.
After increasing the buffer size to 2 bytes, the exposure setting appeared again.
link to the Russian-speaking forum archlinux: https://archlinux.org.ru/forum/topic/18581/

patch:

--- a/drivers/media/usb/uvc/uvc_ctrl.c 2018-06-23 15:12:25.948081416 +0400
+++ b/drivers/media/usb/uvc/uvc_ctrl.c 2018-06-23 14:57:52.462048382 +0400
@@ -1600,12 +1600,12 @@
u8 *data;
int ret;

- data = kmalloc(1, GFP_KERNEL);
+ data = kmalloc(2, GFP_KERNEL);
if (data == NULL)
return -ENOMEM;

ret = uvc_query_ctrl(dev, UVC_GET_INFO, ctrl->entity->id, dev->intfnum,
- info->selector, data, 1);
+ info->selector, data, 2);
if (!ret)
info->flags = UVC_CTRL_FLAG_GET_MIN | UVC_CTRL_FLAG_GET_MAX
| UVC_CTRL_FLAG_GET_RES | UVC_CTRL_FLAG_GET_DEF