Hello, I encountered a "can't wake_up" problem when use camera on imx6. if delay some time after 'streamon' the /dev/video0, then add fd through epoll_ctl, then the process can't be waken_up after some time. I checked both the epoll / vb2_poll(videobuf2_core.c) code. epoll will pass 'poll_table' structure to vb2_poll, but it only contain valid function pointer when inserting fd. in vb2_poll, if found new data in done list, it will not call 'poll_wait'. after that, every call to vb2_poll will not contain valid poll_table, which will result in all calling to poll_wait will not work. so if app can process frames quickly, and found frame data when inserting fd (i.e. poll_wait will not be called or not contain valid function pointer), it will not found valid frame in 'vb2_poll' finally at some time, then call 'poll_wait' to expect be waken up at following vb2_buffer_done, but no good luck. I also checked the 'videobuf-core.c', there is no this problem. of course, both epoll and vb2_poll are right by itself side, but the result is we can't get new frames. I think by epoll's implementation, the user should always call poll_wait. and it's better to split the two actions: 'wait' and 'poll' both for epoll framework and all epoll users, for example, v4l2. am I right? Yi Qingliang
