drm/i915: Skip vblank wait if cxsr was already off
Before we attempt to turn any planes on or off we must first exit
csxr. That's due to cxsr effectively making the plane enable bits
read-only. Currently we achieve that with a vblank wait right after
toggling the cxsr enable bit. We do the vblank wait even if cxsr was
already off, which seems wasteful, so let's try to only do it when
absolutely necessary.
We could start tracking the cxsr state fully somewhere, but for now
it seems easiest to just have intel_set_memory_cxsr() return the
previous cxsr state.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1480354637-14209-11-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 4c4882f..231f099 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5021,10 +5021,9 @@ intel_pre_disable_primary_noatomic(struct drm_crtc *crtc)
* event which is after the vblank start event, so we need to have a
* wait-for-vblank between disabling the plane and the pipe.
*/
- if (HAS_GMCH_DISPLAY(dev_priv)) {
- intel_set_memory_cxsr(dev_priv, false);
+ if (HAS_GMCH_DISPLAY(dev_priv) &&
+ intel_set_memory_cxsr(dev_priv, false))
intel_wait_for_vblank(dev_priv, pipe);
- }
}
static void intel_post_plane_update(struct intel_crtc_state *old_crtc_state)
@@ -5099,10 +5098,9 @@ static void intel_pre_plane_update(struct intel_crtc_state *old_crtc_state)
* event which is after the vblank start event, so we need to have a
* wait-for-vblank between disabling the plane and the pipe.
*/
- if (old_crtc_state->base.active) {
- intel_set_memory_cxsr(dev_priv, false);
+ if (old_crtc_state->base.active &&
+ intel_set_memory_cxsr(dev_priv, false))
intel_wait_for_vblank(dev_priv, crtc->pipe);
- }
}
/*