On Wed, Aug 16, 2017 at 12:03 AM, Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> wrote: > > Hi, > > Rail Shafigulin <rail@xxxxxxxxxxxxxxx> writes: >>> 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 be that the applied patches are outdated, but I just didn't find 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 > > okay, then you need to ask for support from whoever gave you this > kernel. 4.6 is a really old release which this forum doesn't support. > >> When you say UDC (USB Device Controller) driver, what exactly do you mean? > > which driver is g_webcam binding to? What do you have under > /sys/class/udc ? I have this under /sys/class/udc fe200000.dwc3 under /sys/class/udc/fe200000.dwc3 a_alt_hnp_support b_hnp_enable device is_otg maximum_speed srp subsystem a_hnp_support current_speed is_a_peripheral is_selfpowered soft_connect state uevent cat /sys/class/udc/fe200000.dwc3/is_otg 0 cat /sys/class/udc/fe200000.dwc3/is_a_peripheral 0 Given that I configured my board as a device, shouldn't those values be 0? > > [...] > >> Here is what I do on my board: >> >> modprobe g_webcam >> modprobe vivid > > [...] I'm assuming it's this "vivid" driver which isn't in the upstream > kernel and, again, we can't support :-s > > If this is part of an SDK, you've probably already paid for support from > the vendor, I suggest you use their support channel. > > Best of luck > > -- > balbi -- Rail Shafigulin Software Engineer Esencia Technologies -- *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
