When commiting a plane update where the framebuffer doesn't change, we can skip the prepare_fb/cleanup_fb steps. This also allows us to avoid an unnecessary vblank wait at the end of the operation when we're just moving a plane and not changing its image (e.g., for a cursor).
At the moment, i915 is the only upstream driver using the transitional plane helpers, and thus the only driver affected by this change. Reported-by: Jeremiah Mahler <jmmahler at gmail.com> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=88540 Signed-off-by: Matt Roper <matthew.d.roper at intel.com> --- drivers/gpu/drm/drm_plane_helper.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_plane_helper.c b/drivers/gpu/drm/drm_plane_helper.c index f24c4cf..7a5814a 100644 --- a/drivers/gpu/drm/drm_plane_helper.c +++ b/drivers/gpu/drm/drm_plane_helper.c @@ -435,7 +435,8 @@ int drm_plane_helper_commit(struct drm_plane *plane, goto out; } - if (plane_funcs->prepare_fb && plane_state->fb) { + if (plane_funcs->prepare_fb && plane_state->fb && + plane_state->fb != old_fb) { ret = plane_funcs->prepare_fb(plane, plane_state->fb); if (ret) goto out; @@ -456,6 +457,13 @@ int drm_plane_helper_commit(struct drm_plane *plane, crtc_funcs[i]->atomic_flush(crtc[i]); } + /* + * If we only moved the plane and didn't change fb's, there's no need to + * wait for vblank. + */ + if (plane->state->fb == old_fb) + goto out; + for (i = 0; i < 2; i++) { if (!crtc[i]) continue; -- 1.8.5.1
