drm/i915: Don't set persistent FBC mode on ILK/SNB

The ILK/SNB docs are a bit unclear what the persistent mode does, but
the CTG docs clearly state that it was meant to be used when we're
tracking back buffer modifications. We never do that, so leave it in
non-persistent mode.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-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_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 55874d225273cc77504d8e09de82564934118568..87ecf45bef537cc317a63bd1f09ce5e9466ca432 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -230,8 +230,6 @@ static void ironlake_enable_fbc(struct drm_crtc *crtc)
        dpfc_ctl = I915_READ(ILK_DPFC_CONTROL);
        dpfc_ctl &= DPFC_RESERVED;
        dpfc_ctl |= (plane | DPFC_CTL_LIMIT_1X);
-       /* Set persistent mode for front-buffer rendering, ala X. */
-       dpfc_ctl |= DPFC_CTL_PERSISTENT_MODE;
        dpfc_ctl |= DPFC_CTL_FENCE_EN;
        if (IS_GEN5(dev))
                dpfc_ctl |= obj->fence_reg;