drm/i915: Remove delayed FBC activation.

The only time we should start FBC is when we have waited a vblank
after the atomic update. We've already forced a vblank wait by doing
wait_for_flip_done before intel_post_plane_update(), so we don't need
to wait a second time before enabling.

Removing the worker simplifies the code and removes possible race
conditions, like happening in 103167.

Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103167
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180625163758.10871-2-maarten.lankhorst@linux.intel.com
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1659,11 +1659,6 @@ static int i915_fbc_status(struct seq_file *m, void *unused)
 	else
 		seq_printf(m, "FBC disabled: %s\n", fbc->no_fbc_reason);
 
-	if (fbc->work.scheduled)
-		seq_printf(m, "FBC worker scheduled on vblank %llu, now %llu\n",
-			   fbc->work.scheduled_vblank,
-			   drm_crtc_vblank_count(&fbc->crtc->base));
-
 	if (intel_fbc_is_active(dev_priv)) {
 		u32 mask;
 

drivers/gpu/drm/i915/i915_drv.h

@@ -580,12 +580,6 @@ struct intel_fbc {
 		unsigned int gen9_wa_cfb_stride;
 	} params;
 
-	struct intel_fbc_work {
-		bool scheduled;
-		u64 scheduled_vblank;
-		struct work_struct work;
-	} work;
-
 	const char *no_fbc_reason;
 };
 

drivers/gpu/drm/i915/intel_fbc.c

@@ -399,101 +399,13 @@ bool intel_fbc_is_active(struct drm_i915_private *dev_priv)
 	return dev_priv->fbc.active;
 }
 
-static void intel_fbc_work_fn(struct work_struct *__work)
-{
-	struct drm_i915_private *dev_priv =
-		container_of(__work, struct drm_i915_private, fbc.work.work);
-	struct intel_fbc *fbc = &dev_priv->fbc;
-	struct intel_fbc_work *work = &fbc->work;
-	struct intel_crtc *crtc = fbc->crtc;
-	struct drm_vblank_crtc *vblank = &dev_priv->drm.vblank[crtc->pipe];
-
-	if (drm_crtc_vblank_get(&crtc->base)) {
-		/* CRTC is now off, leave FBC deactivated */
-		mutex_lock(&fbc->lock);
-		work->scheduled = false;
-		mutex_unlock(&fbc->lock);
-		return;
-	}
-
-retry:
-	/* Delay the actual enabling to let pageflipping cease and the
-	 * display to settle before starting the compression. Note that
-	 * this delay also serves a second purpose: it allows for a
-	 * vblank to pass after disabling the FBC before we attempt
-	 * to modify the control registers.
-	 *
-	 * WaFbcWaitForVBlankBeforeEnable:ilk,snb
-	 *
-	 * It is also worth mentioning that since work->scheduled_vblank can be
-	 * updated multiple times by the other threads, hitting the timeout is
-	 * not an error condition. We'll just end up hitting the "goto retry"
-	 * case below.
-	 */
-	wait_event_timeout(vblank->queue,
-		drm_crtc_vblank_count(&crtc->base) != work->scheduled_vblank,
-		msecs_to_jiffies(50));
-
-	mutex_lock(&fbc->lock);
-
-	/* Were we cancelled? */
-	if (!work->scheduled)
-		goto out;
-
-	/* Were we delayed again while this function was sleeping? */
-	if (drm_crtc_vblank_count(&crtc->base) == work->scheduled_vblank) {
-		mutex_unlock(&fbc->lock);
-		goto retry;
-	}
-
-	intel_fbc_hw_activate(dev_priv);
-
-	work->scheduled = false;
-
-out:
-	mutex_unlock(&fbc->lock);
-	drm_crtc_vblank_put(&crtc->base);
-}
-
-static void intel_fbc_schedule_activation(struct intel_crtc *crtc)
-{
-	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	struct intel_fbc *fbc = &dev_priv->fbc;
-	struct intel_fbc_work *work = &fbc->work;
-
-	WARN_ON(!mutex_is_locked(&fbc->lock));
-	if (WARN_ON(!fbc->enabled))
-		return;
-
-	if (drm_crtc_vblank_get(&crtc->base)) {
-		DRM_ERROR("vblank not available for FBC on pipe %c\n",
-			  pipe_name(crtc->pipe));
-		return;
-	}
-
-	/* It is useless to call intel_fbc_cancel_work() or cancel_work() in
-	 * this function since we're not releasing fbc.lock, so it won't have an
-	 * opportunity to grab it to discover that it was cancelled. So we just
-	 * update the expected jiffy count. */
-	work->scheduled = true;
-	work->scheduled_vblank = drm_crtc_vblank_count(&crtc->base);
-	drm_crtc_vblank_put(&crtc->base);
-
-	schedule_work(&work->work);
-}
-
 static void intel_fbc_deactivate(struct drm_i915_private *dev_priv,
 				 const char *reason)
 {
 	struct intel_fbc *fbc = &dev_priv->fbc;
 
 	WARN_ON(!mutex_is_locked(&fbc->lock));
 
-	/* Calling cancel_work() here won't help due to the fact that the work
-	 * function grabs fbc->lock. Just set scheduled to false so the work
-	 * function can know it was cancelled. */
-	fbc->work.scheduled = false;
-
 	if (fbc->active)
 		intel_fbc_hw_deactivate(dev_priv);
 
@@ -1005,7 +917,7 @@ static void __intel_fbc_post_update(struct intel_crtc *crtc)
 
 	if (!fbc->busy_bits) {
 		intel_fbc_deactivate(dev_priv, "FBC enabled (active or scheduled)");
-		intel_fbc_schedule_activation(crtc);
+		intel_fbc_hw_activate(dev_priv);
 	} else
 		intel_fbc_deactivate(dev_priv, "frontbuffer write");
 }
@@ -1212,8 +1124,6 @@ void intel_fbc_disable(struct intel_crtc *crtc)
 	if (fbc->crtc == crtc)
 		__intel_fbc_disable(dev_priv);
 	mutex_unlock(&fbc->lock);
-
-	cancel_work_sync(&fbc->work.work);
 }
 
 /**
@@ -1235,8 +1145,6 @@ void intel_fbc_global_disable(struct drm_i915_private *dev_priv)
 		__intel_fbc_disable(dev_priv);
 	}
 	mutex_unlock(&fbc->lock);
-
-	cancel_work_sync(&fbc->work.work);
 }
 
 static void intel_fbc_underrun_work_fn(struct work_struct *work)
@@ -1387,12 +1295,10 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
 {
 	struct intel_fbc *fbc = &dev_priv->fbc;
 
-	INIT_WORK(&fbc->work.work, intel_fbc_work_fn);
 	INIT_WORK(&fbc->underrun_work, intel_fbc_underrun_work_fn);
 	mutex_init(&fbc->lock);
 	fbc->enabled = false;
 	fbc->active = false;
-	fbc->work.scheduled = false;
 
 	if (need_fbc_vtd_wa(dev_priv))
 		mkwrite_device_info(dev_priv)->has_fbc = false;