Hans Verkuil wrote: >>>>> There is a crucial piece of functionality missing here: if the >>>>> filehandle is in blocking mode, then it should wait until an event >>>>> arrives. That also means that if vfh->events == NULL, you should >>> still >>>>> call v4l2_event_dequeue, and that function should initialize >>>>> vfh->events and wait for an event if the fh is in blocking mode. >>>> >>>> I originally left this out intentionally. Most applications using >>> events >>>> would use select / poll as well by default. For completeness it should >>>> be there, I agree. >>> >>> It has to be there. This is important functionality. For e.g. ivtv I >>> would >>> use this to wait until the MPEG decoder flushed all buffers and >>> displayed >>> the last frame of the stream. That's something you would often do in >>> blocking mode. >> >> Blocking mode can easily be emulated using select(). It's quite simple to implement still so I'll do that in the VIDIOC_DQEVENT. Easier for applications anyway in use cases that I haven't been thinking about, e.g. ivtv. >>>> This btw. suggests that we perhaps should put back the struct file >>>> argument for the event functions in video_ioctl_ops. The blocking flag >>>> is indeed part of the file structure. I'm open to better suggestions, >>>> too. >>> >>> My long term goal is that the file struct is only used inside >>> v4l2-ioctl.c >>> and not in drivers. Drivers should not need this struct at all. The >>> easiest >>> way to ensure this is by not passing it to the drivers at all :-) >> >> Drivers still need a way to access the blocking flag. The interim solution >> of >> adding a file * member to v4l2_fh would allow that, while still removing >> most >> usage of file * from drivers. > > Why not just add a 'blocking' argument to the v4l2_event_dequeue? And let > v4l2-ioctl.c fill in that argument? That's how I would do it. Implemented already before reading your mail... :-) I'll try to repost the patches today. -- Sakari Ailus sakari.ailus@xxxxxxxxxxxxxxxxxxxxxxxxxx -- 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
