Hi, On Wed, Jul 20, 2016 at 05:44:56PM +0300, Matwey V. Kornilov wrote: > 2016-07-20 17:13 GMT+03:00 Bin Liu <b-liu@xxxxxx>: > > Hi, > > > > On Wed, Jul 20, 2016 at 09:09:42AM +0300, Matwey V. Kornilov wrote: > >> 2016-07-20 0:34 GMT+03:00 Bin Liu <b-liu@xxxxxx>: > >> > Hi, > >> > > >> > On Wed, Jul 20, 2016 at 12:25:44AM +0300, Matwey V. Kornilov wrote: > >> >> 2016-07-19 23:56 GMT+03:00 Bin Liu <b-liu@xxxxxx>: > >> >> > Hi, > >> >> > > >> >> > On Tue, Jul 19, 2016 at 11:21:17PM +0300, matwey@xxxxxxxxxx wrote: > >> >> >> Hello, > >> >> >> > >> >> >> I have Philips SPC 900 camera (0471:0329) connected to my AM335x based BeagleBoneBlack SBC. > >> >> >> I am sure that both of them are fine and work properly. > >> >> >> I am running Linux 4.6.4 (my kernel config is available at https://clck.ru/A2kQs ) and I've just discovered, that there is an issue with frame transfer when high resolution formats are used. > >> >> >> > >> >> >> The issue is the following. I use simple v4l2 example tool (taken from API docs), which source code is available at http://pastebin.com/grcNXxfe > >> >> >> > >> >> >> When I use (see line 488) 640x480 frames > >> >> >> > >> >> >> fmt.fmt.pix.width = 640; > >> >> >> fmt.fmt.pix.height = 480; > >> >> >> > >> >> >> then I get "select timeout" and don't get any frames. > >> >> >> > >> >> >> When I use 320x240 frames > >> >> >> > >> >> >> fmt.fmt.pix.width = 320; > >> >> >> fmt.fmt.pix.height = 240; > >> >> >> > >> >> >> then about 60% frames are missed. An example outpout of ./a.out -f is available at https://yadi.sk/d/aRka8xWPtSc4y > >> >> >> It looks like there are pauses between bulks of frames (frame counter and timestamp as returned from v4l2 API): > >> >> >> > >> >> >> 3 3705.142553 > >> >> >> 8 3705.342533 > >> >> >> 13 3705.542517 > >> >> >> 110 3708.776208 > >> >> >> 115 3708.976190 > >> >> >> 120 3709.176169 > >> >> >> 125 3709.376152 > >> >> >> 130 3709.576144 > >> >> >> 226 3712.807848 > >> >> >> > >> >> >> When I use tiny 160x120 frames > >> >> >> > >> >> >> fmt.fmt.pix.width = 160; > >> >> >> fmt.fmt.pix.height = 120; > >> >> >> > >> >> >> then more frames are received. See output example at https://yadi.sk/d/DedBmH6ftSc9t > >> >> >> That is why I thought that everything was fine in May when used tiny xawtv window to check kernel OOPS presence (see http://www.spinics.net/lists/linux-usb/msg141188.html for reference) > >> >> >> > >> >> >> Even more. When I introduce USB hub between the host and the webcam, I can not receive even any 320x240 frames. > >> >> >> > >> >> >> I've managed to use ftrace to see what is going on when no frames are received. > >> >> >> I've found that pwc_isoc_handler is called frequently as the following: > >> >> >> > >> >> >> 0) | pwc_isoc_handler [pwc]() { > >> >> >> 0) | usb_submit_urb [usbcore]() { > >> >> >> 0) | usb_submit_urb.part.3 [usbcore]() { > >> >> >> 0) | usb_hcd_submit_urb [usbcore]() { > >> >> >> 0) 0.834 us | usb_get_urb [usbcore](); > >> >> >> 0) | musb_map_urb_for_dma [musb_hdrc]() { > >> >> >> 0) 0.792 us | usb_hcd_map_urb_for_dma [usbcore](); > >> >> >> 0) 5.750 us | } > >> >> >> 0) | musb_urb_enqueue [musb_hdrc]() { > >> >> >> 0) 0.750 us | _raw_spin_lock_irqsave(); > >> >> >> 0) | usb_hcd_link_urb_to_ep [usbcore]() { > >> >> >> 0) 0.792 us | _raw_spin_lock(); > >> >> >> 0) 0.791 us | _raw_spin_unlock(); > >> >> >> 0) + 10.500 us | } > >> >> >> 0) 0.791 us | _raw_spin_unlock_irqrestore(); > >> >> >> 0) + 25.375 us | } > >> >> >> 0) + 45.208 us | } > >> >> >> 0) + 51.042 us | } > >> >> >> 0) + 56.084 us | } > >> >> >> 0) + 61.292 us | } > >> >> >> > >> >> >> However, pwc_isoc_handler never calls vb2_buffer_done() that is why I get "select timeout" in userspace. > >> >> >> Unfortunately, my kernel is not compiled with CONFIG_USB_PWC_DEBUG=y but I can recompile it, if you think that it could provide more information. I am also ready to perform additional tests (use usbmon maybe?). > >> >> >> > >> >> >> How could this issue be resolved? > >> >> >> > >> >> >> Thank you. > >> >> > > >> >> > Do you have CPPI DMA enabled? If so I think you might hit on a known > >> >> > issue in CPPI Isoch transfer, in which the MUSB controller only sends IN > >> >> > tokens in every other SOF, so only half of the bus bandwidth is > >> >> > utilized, which causes video frame drops in higher resolution. > >> >> > > >> >> > >> >> Yes, I do use DMA: > >> >> > >> >> CONFIG_USB_TI_CPPI41_DMA=y > >> > > >> > Okay. > >> > > >> >> > >> >> > To confirm this, use a bus analyzer to capture a bus trace, you would > >> >> > see no IN tokens in every other SOF while transfering Isoch packets. > >> >> > > >> >> > >> >> I am sorry, I am new to USB debugging. Do you mean I need to use > >> >> usbmon or some external hardware device? > >> > > >> > I barely use usbmon, and not sure if it gives the information I am > >> > looking for. But I meant the external test equipment - USB bus protocol > >> > analyzer - a bus packet sniffer. > >> > > >> > >> Now I see. I've googled it, they start from $1000, I don't know > >> when/whether/where I can get one to try. > > > > I think you might be able to check it without a sniffer - MUSB > > controller can generate SOF interrupts, but it is masked in current > > driver. So I think you could enable SOF interrupt, then if you get a log > > as > > SOF > > rx packet > > SOF > > rx packet > > SOF > > ... > > or > > SOF > > rx packet > > rx packet > > rx packet > > SOF > > rx packet > > rx packet > > rx packet > > SOF > > ... > > > > which means your issue is different from the one I mentioned. But if > > you get a log as > > > > SOF > > rx packet > > SOF > > SOF <--- no rx packets in two consecutive SOFs > > rx packet > > SOF > > SOF > > > > then you hit on the known issue I mentioned. > > > >> Until that, could I check something else? For instance, disable > >> CONFIG_USB_TI_CPPI41_DMA. > > > > You could disable it, but I don't think you will get yuv video stream > > of 640x480@30fps. PIO mode does not support such high bandwidth. What is > > your video requirement anyway? > > Many thanks for your guidance. I will answer the rest later when will > be ready to play with SOF interrupt. > Now, I would like to say that use_dma=0 doesn't change the behaviour: > > # cat /sys/module/musb_hdrc/parameters/use_dma > N It sounds like you have a different issue here. With usb_dma=0, I remembered I can get 320x240 YUV stream @30fps from uvc cameras. > > I would like 640x480@5fps which works with x86 based PC. Issue here, > that I can not obtain 640x480 at any FPS on musb. The current CPPI41 driver should be able to handle this. I think you really have to debug the pwc driver to figure out why it drops the video frame. I personally don't have a pwc supported camera, never looked the pwc driver... > > > > >> > >> I've found that after hours of transmit, the camera stops iso at all > >> (until reset). Maybe its brain becomes damaged by the transfer issues > > > > How did you check that? MUSB stopped generating RX EP interrupt? > > Something like that, I suppose. Normally, I see input data flow in > usbmon, but don't see frames in v4l2. > But when camera 'hungs', I don't see nor input flow (except the > control packages exchange) neither frames. Fair enough. Regards, -Bin. -- 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
