On 04/15/2014 08:04 AM, Thomas Scheuermann wrote: > Hi Laurent, > > On 11.04.2014 07:56, Thomas Scheuermann wrote: >> Hi Laurent, >> >> On 07.04.2014 01:37, Laurent Pinchart wrote: >>> Hi Thomas, >>> >>> On Friday 04 April 2014 20:01:33 Scheuermann, Mail wrote: >>>> Hi Laurent, >>>> >>>> I've done the following: >>>> >>>> echo 3 >/sys/module/videobuf2_core/parameters/debug >>>> >>>> and found in /var/log/kern.log after starting my program: >>>> >>>> [239432.535077] vb2: Buffer 0, plane 0 offset 0x00000000 >>>> [239432.535080] vb2: Buffer 1, plane 0 offset 0x001c2000 >>>> [239432.535082] vb2: Buffer 2, plane 0 offset 0x00384000 >>>> [239432.535083] vb2: Allocated 3 buffers, 1 plane(s) each >>>> [239432.535085] vb2: qbuf: userspace address for plane 0 changed, >>>> reacquiring memory >>>> [239432.535087] vb2: qbuf: failed acquiring userspace memory for >>>> plane 0 >>> This confirms everything is working properly up to the point where >>> videobuf2- >>> vmalloc fails to acquire the user pointer memory. The problem comes from >>> vb2_vmalloc_get_userptr() in >>> drivers/media/v4l2-core/videobuf2-vmalloc.c. >>> Unfortunately that function lacks debugging. Are you familiar enough >>> with >>> kernel programming to add printk statements there and see where it >>> fails ? >> I was able to put some debug output in vb2_vmalloc_get_userptr. >> A call to 'vb2_get_contig_userptr' failed. Unless I am mistaken vb2_get_contig_userptr() requires that the userptr points to physically contiguous memory, but that should not be a requirement for videobuf2-vmalloc. Pawel, any idea why vb2_get_contig_userptr() is used here? Regards, Hans >> I will also put some debug code there to get more information. > > In vb2_get_contig_userptr I saw that the call to 'follow_pfn' failed and > returned -22. > Do you know what the problem here is? >>>> [239432.535088] vb2: qbuf: buffer preparation failed: -22 >>>> [239432.535128] vb2: streamoff: not streaming >> >> This message is subject to the following terms and conditions: MAIL >> DISCLAIMER<http://www.barco.com/en/maildisclaimer> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-media" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > This message is subject to the following terms and conditions: MAIL DISCLAIMER<http://www.barco.com/en/maildisclaimer> > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
