Tegra would not only need a hardware vblank counter that increments at leading edge of vblank, but also support for instantaneous high precision vblank timestamp queries, ie. a proper implementation of dev->driver->get_vblank_timestamp().
Without these, there can be off-by-one errors during vblank disable/enable if the scanout is inside vblank at en/disable time, and additionally clients will never see any useable vblank timestamps when querying via drmWaitVblank ioctl. This would negatively affect swap scheduling under X11 and Wayland.
Signed-off-by: Mario Kleiner mario.kleiner.de@gmail.com Cc: Thierry Reding treding@nvidia.com Cc: Dave Airlie airlied@redhat.com --- drivers/gpu/drm/tegra/drm.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c index 1833abd..bfad15a 100644 --- a/drivers/gpu/drm/tegra/drm.c +++ b/drivers/gpu/drm/tegra/drm.c @@ -173,7 +173,6 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags) drm->irq_enabled = true;
/* syncpoints are used for full 32-bit hardware VBLANK counters */ - drm->vblank_disable_immediate = true; drm->max_vblank_count = 0xffffffff;
err = drm_vblank_init(drm, drm->mode_config.num_crtc);