[sane-devel] Experience with the v4l backend?

[doark at mail.com]

On 02/04/2017(Sat) 07:10
Torfinn Ingolfsen <tingox at gmail.com> wrote:

> To: sane-devel at lists.alioth.debian.org
> Subject: Re: [sane-devel] Experience with the v4l backend?
> Date: 
> 
> On Wed, Feb 1, 2017 at 3:56 PM,  <doark at mail.com> wrote:
> >
> > I can't take a gray scale image with my usb cam either.
> > I'd guess that this is a bug.  
> 
> Possibly, yes.
> 
> > I fact, I can only take one image and then the second generates an
> > error.  
> 
> Ok, that is a bug. The question is if it is a bug with sane or with
> the device itself.
Sorry, catching up with my mail.

> Does the device (usb cam) worh with other programs after taking an
> image with sane first?
I'm not sure, now I can't scan at all via the v4l.
I just tried, scanimage reported an I/O error, and the kernel has spat
out a bunch of info:

Mar 15 03:02:01 [kernel] [1165605.488904] uvcvideo: Failed to query (131)
UVC probe control : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.493100] uvcvideo: Failed to set UVC
probe control : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.500103] uvcvideo: Failed to set
UVC probe control : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.504359] uvcvideo: Failed to set UVC
probe cont rol : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.508605] uvcvideo: Failed to set
UVC probe control : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.512880] uvcvideo: Failed to set UVC
probe control : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.517106] uvcvideo: Failed to query
(GET_CUR) UVC control 6 on unit 2: -71 (exp. 2).
Mar 15 03:02:01 [kernel] [1165605.521358] uvcvideo: Failed to query
(SET_CUR) UVC control 2 on unit 2: -71 (exp. 2).
Mar 15 03:02:01 [kernel] [1165605.525609] uvcvideo:
Failed to query (SET_CUR) UVC control 6 on unit 2: -71 (exp. 2).
Mar 15 03:02:01 [kernel] [1165605.529862] uvcvideo: Failed to query
(SET_CUR) UVC control 3 on unit 2: -71 (exp. 2).
Mar 15 03:02:01 [kernel] [1165605.534104] uvcvideo: Failed to query
(SET_CUR) UVC control 7 on unit 2: -71 (exp. 2).
Mar 15 03:02:01 [kernel] [1165605.538355] uvcvideo:
Failed to query (SET_CUR) UVC control 9 on unit 2: -71 (exp. 2).
Mar 15 03:02:01 [kernel] [1165605.542611] uvcvideo: Failed to set UVC
probe control : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.546853] uvcvideo: Failed to set UVC
probe control : -71 (exp. 26).
Mar 15 03:02:01 [kernel] [1165605.577255] usb 3-1.3: USB disconnect,
device number 82

Now /dev/video0 has vanished and sane reports no v4l.

It could really be the cam, most of this laptop has broken (and only
after 2 years ):

It's not a huge issue for me, I hardly used it anyway.

Thanks,
David