drm/i915: kill intel_clear_scanline_wait

This is a pretty racy way to close these races, and we have
much better means to cope with these races meanwhile: For
non-broken userspace we correctly wait for any outstanding
rendering, for broken userspace the hangcheck will save the
day.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
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 278c0f071585932a1da4eb6ccfd748b060f74926..2617ab580dff13383aebbfad8a430e6f91515ac1 100644 (file)
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2528,26 +2528,6 @@ static void ironlake_fdi_disable(struct drm_crtc *crtc)
        udelay(100);
 }
 
-/*
- * When we disable a pipe, we need to clear any pending scanline wait events
- * to avoid hanging the ring, which we assume we are waiting on.
- */
-static void intel_clear_scanline_wait(struct drm_device *dev)
-{
-       struct drm_i915_private *dev_priv = dev->dev_private;
-       struct intel_ring_buffer *ring;
-       u32 tmp;
-
-       if (IS_GEN2(dev))
-               /* Can't break the hang on i8xx */
-               return;
-
-       ring = LP_RING(dev_priv);
-       tmp = I915_READ_CTL(ring);
-       if (tmp & RING_WAIT)
-               I915_WRITE_CTL(ring, tmp);
-}
-
 static void intel_crtc_wait_for_pending_flips(struct drm_crtc *crtc)
 {
        struct drm_device *dev = crtc->dev;
@@ -2931,7 +2911,6 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
 
        mutex_lock(&dev->struct_mutex);
        intel_update_fbc(dev);
-       intel_clear_scanline_wait(dev);
        mutex_unlock(&dev->struct_mutex);
 }
 
@@ -3036,7 +3015,6 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
        intel_crtc->active = false;
        intel_update_fbc(dev);
        intel_update_watermarks(dev);
-       intel_clear_scanline_wait(dev);
 }
 
 static void i9xx_crtc_dpms(struct drm_crtc *crtc, int mode)