On Thu, Mar 05, 2015 at 05:52:50PM -0800, Haixia Shi wrote: > On Thu, Mar 5, 2015 at 2:33 AM, Chris Wilson <chris at chris-wilson.co.uk> > wrote: > > On Wed, Mar 04, 2015 at 06:26:23PM -0800, Haixia Shi wrote: > >> This also limits the maximum frequency of page flips by the vrefresh rate. > >> > >> Signed-off-by: Haixia Shi <hshi at chromium.org> > >> Reviewed-by: Stéphane Marchesin <marcheu at chromium.org> > >> Tested-by: Haixia Shi <hshi at chromium.org> > > > > I think the better approach would have been to push the task down to > > udl_handle_damage(). Almost all of the callers would prefer deferred > > updates (with the notable exception of modesetting). > > -Chris > > I'm not sure this is correct. While there's reasonable expectation for > page flips to be asynchronous (when flip completes it would send the > vblank event), my understanding is that fb_fillrect, fb_copyarea and > fb_imageblit are synchronous.
No, they are not synchronous with monitor refresh. Conceptually running the usb xfer from a timer is the equivalent of the monitor reading from the scanout at a distinct point in time from when we write into the framebuffer. -Chris -- Chris Wilson, Intel Open Source Technology Centre
