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. -- 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
