On Mon, Mar 23, 2015 at 10:14 PM, Devin Heitmueller <dheitmuel...@kernellabs.com> wrote: > > My guess would be that there's some bug in the cx231xx that > exacerbates an edge case in the XHCI core - like prematurely setting > the USB alternate back to zero when stopping streaming and not > canceling all the URBs first. > > ... > > As a test, you may wish to try disabling the cx231xx-audio module. > That will help narrow down an interaction with ALSA, pulseaudio, and > one of the two sources of URB queueing.
I think you're on the right track here - blacklisting the audio module (cx231xxx_alsa) allowed successful video recording with the device inserted during boot. I added some logging to drivers/usb/core/message.c to check that the URB list is empty before changing the alternate interface. While it wasn't ever called with a non-empty list, it did perhaps help narrow down the area of code causing trouble. The normal sequence of log messages when stopping recoring is: Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.866435] cx231xx 1-2:1.1: urb_init=0 dev->video_mode.max_pkt_size=2892 Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.900280] cx231xx 1-2:1.1: urb_init=0 dev->video_mode.max_pkt_size=2892 Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.943487] cx231xx 1-2:1.1: urb_init=0 dev->video_mode.max_pkt_size=2892 Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.988004] cx231xx 1-2:1.1: stopping capture Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.988009] cx231xx 1-2:1.1: Stopping isoc Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.988022] cx231xx 1-2:1.1: Stop capture, if needed Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.988056] cx231xx 1-2:1.1: Stop capture, if needed Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.988058] cx231xx 1-2:1.1: closing device Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.988062] cx231xx 1-2:1.1: cx231xx_stop_stream: ep_mask = 4 Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.988167] usb 1-2: akg URB list: next=0xffff880073299d90, prev=0xffff880073299d90, eq=1, empty=1 Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.993115] cx231xx 1-2:1.1: cx231xx_stop_stream: ep_mask = 8 Mar 26 08:50:41 alistair-XPS13 kernel: [ 771.993192] usb 1-2: akg URB list: next=0xffff8800732992b0, prev=0xffff8800732992b0, eq=1, empty=1 The "akg URB" record is the log I added to usb_set_interface(). The failures appear to have several different paths, however one of them is: Mar 26 08:57:17 alistair-XPS13 kernel: [ 87.915849] cx231xx 1-2:1.1: urb_init=0 dev->video_mode.max_pkt_size=2892 Mar 26 08:57:17 alistair-XPS13 kernel: [ 87.960923] cx231xx 1-2:1.1: urb_init=0 dev->video_mode.max_pkt_size=2892 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.004771] cx231xx 1-2:1.1: urb_init=0 dev->video_mode.max_pkt_size=2892 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032245] cx231xx 1-2:1.1: stopping capture Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032253] cx231xx 1-2:1.1: Stopping isoc Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032273] cx231xx 1-2:1.1: Stop capture, if needed Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032326] cx231xx 1-2:1.1: Stop capture, if needed Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032331] cx231xx 1-2:1.1: closing device Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032337] cx231xx 1-2:1.1: cx231xx_stop_stream: ep_mask = 4 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032526] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not part of current TD ep_index 8 comp_code 1 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032542] xhci_hcd 0000:00:14.0: Looking for event-dma 00000001f8671400 trb-start 00000001facb2090 trb-end 00000001facb2090 seg-start 00000001facb2000 seg-end 00000001facb23f0 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032565] usb 1-2: akg URB list: next=0xffff880215504eb0, prev=0xffff880215504eb0, eq=1, empty=1 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032579] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not part of current TD ep_index 8 comp_code 1 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032596] xhci_hcd 0000:00:14.0: Looking for event-dma 00000001f8671410 trb-start 00000001facb2090 trb-end 00000001facb2090 seg-start 00000001facb2000 seg-end 00000001facb23f0 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032703] xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not part of current TD ep_index 8 comp_code 1 Mar 26 08:57:17 alistair-XPS13 kernel: [ 88.032712] xhci_hcd 0000:00:14.0: Looking for event-dma 00000001f8671420 trb-start 00000001facb2090 trb-end 00000001facb2090 seg-start 00000001facb2000 seg-end 00000001facb23f0 Hopefully this will give some clues about where to look next. Thanks again for all your assistance. Cheers, Alistair -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
