drm/i915: POSTING_READ IPS_CTL before waiting for the vblank

Make sure we write to IPS before we actually wait.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-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 2ed974e..1a4232e 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -3386,6 +3386,7 @@ static void hsw_disable_ips(struct intel_crtc *crtc)
 
        assert_plane_enabled(dev_priv, crtc->plane);
        I915_WRITE(IPS_CTL, 0);
+       POSTING_READ(IPS_CTL);
 
        /* We need to wait for a vblank before we can disable the plane. */
        intel_wait_for_vblank(dev, crtc->pipe);