On Mon, Sep 19, 2016 at 10:56 PM, Michel Dänzer <michel@xxxxxxxxxxx> wrote: > On 17/09/16 09:25 PM, Mario Kleiner wrote: >> Pre DCE4 hw doesn't have reliable pageflip completion >> interrupts, so instead polling for flip completion is >> used from within the vblank irq handler to complete >> page flips. >> >> This causes a race if pageflip ioctl is called close to >> vblank: >> >> 1. pageflip ioctl queues execution of radeon_flip_work_func. >> >> 2. vblank irq fires, radeon_crtc_handle_vblank checks for >> flip_status == FLIP_SUBMITTED finds none, no-ops. >> >> 3. radeon_flip_work_func runs inside vblank, decides to >> set flip_status == FLIP_SUBMITTED and programs the >> flip into hw. >> >> 4. hw executes flip immediately (because in vblank), but >> as 2 already happened, the flip completion routine only >> emits the flip completion event one refresh later -> >> wrong vblank count/timestamp for completion and no >> performance gain, as instead of delaying the flip until >> next vblank, we now delay the next flip by 1 refresh >> while waiting for the delayed flip completion event. >> >> Given we often don't gain anything due to this race, but >> lose precision, prevent the programmed flip from executing >> in vblank on pre DCE4 asics to avoid this race. >> >> On pre-AVIVO hw we can't program the hw for edge-triggered >> flips, they always execute anywhere in vblank. Therefore delay >> the actual flip programming until after vblank on pre-AVIVO. >> >> Signed-off-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx> > > Reviewed-by: Michel Dänzer <michel.daenzer@xxxxxxx> Applied this series. Thanks! Alex > > > P.S. Please send radeon (and amdgpu) driver patches to the amd-gfx > mailing list (as well). > > -- > Earthling Michel Dänzer | http://www.amd.com > Libre software enthusiast | Mesa and X developer > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
