On Tue, Aug 15, 2017 at 2:43 AM, Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> wrote: > > Hi, > > Rail Shafigulin <rail@xxxxxxxxxxxxxxx> writes: >> Let me apologize for emailing directly to the list as I'm not one of >> the developers and just starting out with USB and UVC. After searching > > the list is open to anybody and we welcome newcomers :-) > >> online for about a week I just couldn't find answers and I hope the >> original authors of the uvc-gadget tool are on the list and can help >> out. >> >> Needed to test a UVC in a custom built kernel (Xilinx petalinux), . >> Followed these directions, >> https://github.com/torvalds/linux/blob/ef954844c7ace62f773f4f23e28d2d915adc419f/Documentation/usb/gadget-testing.txt#L717-L730. >> >> Patches didn't work. Had to look around for correct ones. Found them >> here, http://markmail.org/message/hb7evzvigbuxptz5#query:+page:1+mid:s73fdeffjgb2v2yw+state:results. >> >> Combined and applied the patches into a repo here, >> https://github.com/cyboflash/uvc-gadget.git. >> >> When I ran a test command, given in the instructions above, >> uvc-gadget -u /dev/video<uvc video node #> -v /dev/video<vivid video node #> >> >> got the following error: >> V4L2_CORE: (jpeg decoder) error while decoding frame >> >> and a black screen. >> >> One thing to note is that I was not using luvcview, but guvcview. >> >> It looks like the error is coming from here, >> https://sourceforge.net/p/guvcview/git-master/ci/master/tree/gview_v4l2core/jpeg_decoder.c#l1503 >> >> My thoughts >> 1. I don't think the error is coming from v4l2. I tested it on another >> machine and it worked. But I'm not an expert so I can't say for sure. >> 2. I don't think the error is coming from UVC. I think since I see a >> black screen, it is working. Again, I'm not an expert, so I can't say >> for sure. >> 3. I think the error is due to uvc-gadget test application. It could >> be that the applied patches are outdated, but I just didn't find >> anything else online. But, I'm not an expert so definitely can't say >> for sure. >> >> I would greatly appreciate any help with this as I'm just starting out >> with UVC and USB. > > Which kernel are you using? Which UDC driver are you using? Balbi, The board is configured as a USB Camera Gadget. Here is the output of uname -a Linux Xilinx-ZCU102-2016_3 4.6.0 #33 SMP Thu Aug 10 11:47:57 PDT 2017 aarch64 GNU/Linux When you say UDC (USB Device Controller) driver, what exactly do you mean? Here is what I do on my board: modprobe g_webcam modprobe vivid uvc-gadget -u /dev/video0 -v /dev/video1 Where uvc-gadget is precompiled app from here, https://github.com/cyboflash/uvc-gadget.git On my host (Linux ubuntu 4.10.0-32-generic #36~16.04.1-Ubuntu SMP Wed Aug 9 09:19:02 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux) I simply execute the following in my terminal guvcview and then later choose the source for my input. At this point I'm starting to see V4L2_CORE: (jpeg decoder) error while decoding frame. I've tested guvcview with my built-in camera and didn't see any issues. Any help is appreciated. > > -- > balbi -- *ESENCIA TECHNOLOGIES, INC.*3945 Freedom Circle, Suite #360, Santa Clara CA 95054 ________________________________________________________ Phone: +1 408 736 8284 Fax: +1 408 519 3475 http://www.esenciatech.com | http://www.lnttechservices.com -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
