BBB UVC/DMA crash kernel 3.13.6-bone7.1

The USB DMA still appears to have problems when used with USB cameras. It appears that whenever I attempt to issue controls via UVC to a camera that is capturing, then I get the attached crash. PIO mode works fine. Could I suggest that the default defconfig selects PIO mode until DMA mode works reliably?

I hope this is the right place to post. If not, please excuse my intrusion, and suggest another.

Best regards,

Dave.

uvc-dma-crash (15.4 KB)

Done: https://github.com/RobertCNelson/linux-dev/commit/182589dcccc51ae7ecc82c1ba9ef2b6440edf2d9

I don't see it getting completely fixed anytime soon either

Regards,

The USB DMA still appears to have problems when used with USB cameras. It
appears that whenever I attempt to issue controls via UVC to a camera that
is capturing, then I get the attached crash. PIO mode works fine. Could I
suggest that the default defconfig selects PIO mode until DMA mode works
reliably?

I hope this is the right place to post. If not, please excuse my intrusion,
and suggest another.

Done: https://github.com/RobertCNelson/linux-dev/commit/182589dcccc51ae7ecc82c1ba9ef2b6440edf2d9

I don't see it getting completely fixed anytime soon either

That's a shame. I guess it is a known problem then. Just no one working on it? :frowning:

Robert,
     I just tried your 3.14.4-bone4 kernel. Thanks for including my Argus UPS cape patches:-) . It appears that the UVC DMA is getting better, but I am getting the following warning messages when I issue any UVC controls. The good news is that the system still continues to work fine apart from these messages. Close, but no cigar :-\
Please pass on words of encouragement to the developers responsible for this.

Regards,

Dave.

The USB DMA still appears to have problems when used with USB cameras. It
appears that whenever I attempt to issue controls via UVC to a camera that
is capturing, then I get the attached crash. PIO mode works fine. Could I
suggest that the default defconfig selects PIO mode until DMA mode works
reliably?

I hope this is the right place to post. If not, please excuse my intrusion,
and suggest another.

Done: https://github.com/RobertCNelson/linux-dev/commit/182589dcccc51ae7ecc82c1ba9ef2b6440edf2d9

I don't see it getting completely fixed anytime soon either

Regards,

uname -a
Linux trax-jdal 3.14.4-bone4 #1 SMP Mon May 19 15:25:52 CDT 2014 armv7l GNU/Linux
root@trax-jdal:~# [ 238.501234] ------------[ cut here ]------------
[ 238.506128] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:605 cppi41_dma_control+0x2a0/0x2f0()
[ 238.515429] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 238.540705] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 238.548403] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 238.556539] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 238.564121] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 238.572607] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 238.581822] [<c003f0cc>] (warn_slowpath_null) from [<c03bc900>] (cppi41_dma_control+0x2a0/0x2f0)
[ 238.591051] [<c03bc900>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 238.600723] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 238.610942] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 238.620440] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 238.629292] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 238.637818] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 238.647147] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 238.657926] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 238.668979] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 238.678742] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 238.686872] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 238.694813] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 238.702484] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 238.710420] ---[ end trace 4b907c08f9a1b69e ]---
[ 238.715257] ------------[ cut here ]------------
[ 238.720099] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:629 cppi41_dma_control+0x28c/0x2f0()
[ 238.729397] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 238.754654] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 238.762324] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 238.770448] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 238.778024] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 238.786509] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 238.795722] [<c003f0cc>] (warn_slowpath_null) from [<c03bc8ec>] (cppi41_dma_control+0x28c/0x2f0)
[ 238.804939] [<c03bc8ec>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 238.814611] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 238.824829] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 238.834317] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 238.843169] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 238.851664] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 238.860986] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 238.871765] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 238.882809] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 238.892571] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 238.900693] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 238.908633] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 238.916300] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 238.924234] ---[ end trace 4b907c08f9a1b69f ]---
[ 238.929342] ------------[ cut here ]------------
[ 238.934199] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:605 cppi41_dma_control+0x2a0/0x2f0()
[ 238.943499] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 238.968758] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 238.976432] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 238.984559] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 238.992136] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 239.000621] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 239.009835] [<c003f0cc>] (warn_slowpath_null) from [<c03bc900>] (cppi41_dma_control+0x2a0/0x2f0)
[ 239.019053] [<c03bc900>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 239.028725] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 239.038943] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 239.048434] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 239.057284] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 239.065787] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 239.075110] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 239.085890] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 239.096936] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 239.106697] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 239.114820] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 239.122761] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 239.130429] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 239.138364] ---[ end trace 4b907c08f9a1b6a0 ]---
[ 239.143200] ------------[ cut here ]------------
[ 239.148041] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:629 cppi41_dma_control+0x28c/0x2f0()
[ 239.157339] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 239.182592] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 239.190261] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 239.198384] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 239.205961] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 239.214446] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 239.223660] [<c003f0cc>] (warn_slowpath_null) from [<c03bc8ec>] (cppi41_dma_control+0x28c/0x2f0)
[ 239.232875] [<c03bc8ec>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 239.242546] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 239.252764] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 239.262252] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 239.271102] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 239.279598] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 239.288921] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 239.299700] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 239.310744] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 239.320505] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 239.328627] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 239.336566] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 239.344233] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 239.352166] ---[ end trace 4b907c08f9a1b6a1 ]---
[ 239.357604] ------------[ cut here ]------------
[ 239.362470] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:605 cppi41_dma_control+0x2a0/0x2f0()
[ 239.371771] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 239.397035] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 239.404716] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 239.412846] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 239.420424] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 239.428910] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 239.438124] [<c003f0cc>] (warn_slowpath_null) from [<c03bc900>] (cppi41_dma_control+0x2a0/0x2f0)
[ 239.447345] [<c03bc900>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 239.457017] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 239.467234] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 239.476725] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 239.485576] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 239.494085] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 239.503410] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 239.514189] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 239.525237] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 239.534999] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 239.543123] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 239.551065] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 239.558733] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 239.566668] ---[ end trace 4b907c08f9a1b6a2 ]---
[ 239.571503] ------------[ cut here ]------------
[ 239.576344] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:629 cppi41_dma_control+0x28c/0x2f0()
[ 239.585642] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 239.610896] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 239.618565] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 239.626689] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 239.634265] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 239.642750] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 239.651964] [<c003f0cc>] (warn_slowpath_null) from [<c03bc8ec>] (cppi41_dma_control+0x28c/0x2f0)
[ 239.661181] [<c03bc8ec>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 239.670852] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 239.681069] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 239.690559] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 239.699409] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 239.707906] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 239.717227] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 239.728005] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 239.739049] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 239.748810] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 239.756932] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 239.764871] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 239.772539] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 239.780473] ---[ end trace 4b907c08f9a1b6a3 ]---
[ 239.785544] ------------[ cut here ]------------
[ 239.790399] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:605 cppi41_dma_control+0x2a0/0x2f0()
[ 239.799699] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 239.824958] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 239.832632] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 239.840758] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 239.848336] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 239.856821] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 239.866035] [<c003f0cc>] (warn_slowpath_null) from [<c03bc900>] (cppi41_dma_control+0x2a0/0x2f0)
[ 239.875253] [<c03bc900>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 239.884925] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 239.895142] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 239.904632] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 239.913483] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 239.921984] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 239.931308] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 239.942087] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 239.953132] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 239.962893] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 239.971017] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 239.978956] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 239.986624] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 239.994560] ---[ end trace 4b907c08f9a1b6a4 ]---
[ 239.999395] ------------[ cut here ]------------
[ 240.004235] WARNING: CPU: 0 PID: 498 at drivers/dma/cppi41.c:629 cppi41_dma_control+0x28c/0x2f0()
[ 240.013532] Modules linked in: rtc_ds1307 snd_usb_audio snd_usbmidi_lib snd_hwdep snd_rawmidi uvcvideo snd_seq_device snd_pcm videobuf2_vmalloc snd_timer videobuf2_memops snd videobuf2_core soundcore ftdi_sio usbserial omap_aes omap_sham rtc_omap uio_pdrv_genirq uio loop
[ 240.038782] CPU: 0 PID: 498 Comm: python Tainted: G W 3.14.4-bone4 #1
[ 240.046451] [<c0015218>] (unwind_backtrace) from [<c0011bbc>] (show_stack+0x10/0x14)
[ 240.054576] [<c0011bbc>] (show_stack) from [<c06c8788>] (dump_stack+0x80/0x90)
[ 240.062151] [<c06c8788>] (dump_stack) from [<c003f014>] (warn_slowpath_common+0x70/0x8c)
[ 240.070637] [<c003f014>] (warn_slowpath_common) from [<c003f0cc>] (warn_slowpath_null+0x1c/0x24)
[ 240.079850] [<c003f0cc>] (warn_slowpath_null) from [<c03bc8ec>] (cppi41_dma_control+0x28c/0x2f0)
[ 240.089066] [<c03bc8ec>] (cppi41_dma_control) from [<c04dfa78>] (cppi41_dma_channel_abort+0xc8/0x13c)
[ 240.098738] [<c04dfa78>] (cppi41_dma_channel_abort) from [<c04db2a8>] (musb_cleanup_urb.isra.12+0x40/0x10c)
[ 240.108954] [<c04db2a8>] (musb_cleanup_urb.isra.12) from [<c04db5b4>] (musb_urb_dequeue+0xe8/0x128)
[ 240.118443] [<c04db5b4>] (musb_urb_dequeue) from [<c04c0bd0>] (usb_hcd_unlink_urb+0x4c/0x84)
[ 240.127294] [<c04c0bd0>] (usb_hcd_unlink_urb) from [<c04c1d74>] (usb_kill_urb+0x50/0xcc)
[ 240.135791] [<c04c1d74>] (usb_kill_urb) from [<bf0b8c08>] (uvc_uninit_video+0x34/0x60 [uvcvideo])
[ 240.145113] [<bf0b8c08>] (uvc_uninit_video [uvcvideo]) from [<bf0baff0>] (uvc_video_enable+0x18/0x168 [uvcvideo])
[ 240.155891] [<bf0baff0>] (uvc_video_enable [uvcvideo]) from [<bf0b7fbc>] (uvc_v4l2_do_ioctl+0x5b8/0x1180 [uvcvideo])
[ 240.166936] [<bf0b7fbc>] (uvc_v4l2_do_ioctl [uvcvideo]) from [<c0517560>] (video_usercopy+0x194/0x53c)
[ 240.176697] [<c0517560>] (video_usercopy) from [<c0513344>] (v4l2_ioctl+0x114/0x13c)
[ 240.184819] [<c0513344>] (v4l2_ioctl) from [<c0156d60>] (do_vfs_ioctl+0x400/0x5c4)
[ 240.192760] [<c0156d60>] (do_vfs_ioctl) from [<c0156f90>] (SyS_ioctl+0x6c/0x7c)
[ 240.200426] [<c0156f90>] (SyS_ioctl) from [<c000e1a0>] (ret_fast_syscall+0x0/0x30)
[ 240.208359] ---[ end trace 4b907c08f9a1b6a5 ]---

Unfortunately I seem to have spoken too soon. After multiple control commands, the UVC subsystem becomes unresponsive. Could I suggest making the default "PIO only" again?

Regards,

Dave.

Sure, I can do that. I Actually thought that was the default in my
v3.14.4 branch, I guess I've been spending too much time with
v3.15-rcX..

https://github.com/RobertCNelson/bb-kernel/commit/fbe2858bfe0f112511b45a6c1ecf9c111ef6f47f

Regards,