[Intel-gfx] [PATCH] drm/i915: Treat resetting of the current framebuffer as a no-op

[Chris Wilson]

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 at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_display.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 981549c..f4450f1 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2286,6 +2286,11 @@ 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,
-- 
1.7.10.4