On Sat, Mar 3, 2012 at 01:23, Sakari Ailus sakari.ailus@iki.fi wrote:
Where it should be decided which operations are being done to the buffer when it is passed to user space and back to kernel space?
How about spliting these operations to those done on the first time the buffer is passed to the user space (mapping to kernel address space, for example) and those required every time buffer is passed from kernel to user and back (cache flusing)?
I'm asking since any unnecessary time-consuming operations, especially as heavy as mapping the buffer, should be avoidable in subsystems dealing with streaming video, cameras etc., i.e. non-GPU users.
I'm a bit confused about your comments because this interface extension doesn't support userspace mmap. So userspace isn't even part of the picture. Adding mmap support is something entirely different imo, and I have no idea yet how we should handle cache coherency for that.
Yours, Daniel