drm/i915: Treat resetting of the current framebuffer as a no-op

If none of the CRTC parameters change along with the framebuffer, we can
forgo rewriting the register and waiting for a vblank. There are a few
calls made by the display managers as they start up which tend to end up
performing no-ops on the current CRTC settings.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 2a9d0671f8c382b433f141588c1701a3dbf74951..d63bb3fa3d419c9ddd58f8d7ea408687b5080290 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2188,6 +2188,11 @@ intel_pipe_set_base(struct drm_crtc *crtc, int x, int y,
                return -EINVAL;
        }
 
+       if (fb == crtc->fb && crtc->x == x && crtc->y == y) {
+               DRM_DEBUG_KMS("skipping reset of current fb");
+               return 0;
+       }
+
        mutex_lock(&dev->struct_mutex);
        ret = intel_pin_and_fence_fb_obj(dev,
                                         to_intel_framebuffer(fb)->obj,