drm/i915: Fix watermarks for VLV/CHV

commit 92826fcdfc14 ("drm/i915: Calculate watermark related members in the crtc_state, v4.")
broke thigns by removing the pre vs. post wm update distinction. We also
lost the pre plane wm update entirely for VLV/CHV from the crtc enable
path.

This caused underruns on modeset and plane enable/disable on CHV,
and often those can lead to a dead pipe.

So let's bring back the pre vs. post thing, and let's toss in an
explicit wm update to valleyview_crtc_enable() to avoid having to
put it into the common code.

This is more or less a partial revert of the offending commit.

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: drm-intel-fixes@lists.freedesktop.org
Fixes: 92826fcdfc14 ("drm/i915: Calculate watermark related members in the crtc_state, v4.")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1457543247-13987-4-git-send-email-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/i915/intel_atomic.c

@@ -96,7 +96,8 @@ intel_crtc_duplicate_state(struct drm_crtc *crtc)
 	crtc_state->update_pipe = false;
 	crtc_state->disable_lp_wm = false;
 	crtc_state->disable_cxsr = false;
-	crtc_state->wm_changed = false;
+	crtc_state->update_wm_pre = false;
+	crtc_state->update_wm_post = false;
 	crtc_state->fb_changed = false;
 	crtc_state->wm.need_postvbl_update = false;
 

drivers/gpu/drm/i915/intel_display.c

@@ -4677,7 +4677,7 @@ static void intel_post_plane_update(struct intel_crtc *crtc)
 
 	crtc->wm.cxsr_allowed = true;
 
-	if (pipe_config->wm_changed && pipe_config->base.active)
+	if (pipe_config->update_wm_post && pipe_config->base.active)
 		intel_update_watermarks(&crtc->base);
 
 	if (atomic->update_fbc)
@@ -4759,7 +4759,7 @@ static void intel_pre_plane_update(struct intel_crtc_state *old_crtc_state)
 	 */
 	if (dev_priv->display.initial_watermarks != NULL)
 		dev_priv->display.initial_watermarks(pipe_config);
-	else if (pipe_config->wm_changed)
+	else if (pipe_config->update_wm_pre)
 		intel_update_watermarks(&crtc->base);
 }
 
@@ -6130,6 +6130,7 @@ static void valleyview_crtc_enable(struct drm_crtc *crtc)
 
 	intel_crtc_load_lut(crtc);
 
+	intel_update_watermarks(crtc);
 	intel_enable_pipe(intel_crtc);
 
 	assert_vblank_disabled(crtc);
@@ -11776,19 +11777,27 @@ int intel_plane_atomic_calc_changes(struct drm_crtc_state *crtc_state,
 			 plane->base.id, was_visible, visible,
 			 turn_off, turn_on, mode_changed);
 
-	if (turn_on || turn_off) {
-		pipe_config->wm_changed = true;
+	if (turn_on) {
+		pipe_config->update_wm_pre = true;
+
+		/* must disable cxsr around plane enable/disable */
+		if (plane->type != DRM_PLANE_TYPE_CURSOR)
+			pipe_config->disable_cxsr = true;
+	} else if (turn_off) {
+		pipe_config->update_wm_post = true;
 
 		/* must disable cxsr around plane enable/disable */
 		if (plane->type != DRM_PLANE_TYPE_CURSOR)
 			pipe_config->disable_cxsr = true;
 	} else if (intel_wm_need_update(plane, plane_state)) {
-		pipe_config->wm_changed = true;
+		/* FIXME bollocks */
+		pipe_config->update_wm_pre = true;
+		pipe_config->update_wm_post = true;
 	}
 
 	/* Pre-gen9 platforms need two-step watermark updates */
-	if (pipe_config->wm_changed && INTEL_INFO(dev)->gen < 9 &&
-	    dev_priv->display.optimize_watermarks)
+	if ((pipe_config->update_wm_pre || pipe_config->update_wm_post) &&
+	    INTEL_INFO(dev)->gen < 9 && dev_priv->display.optimize_watermarks)
 		to_intel_crtc_state(crtc_state)->wm.need_postvbl_update = true;
 
 	if (visible || was_visible)
@@ -11888,7 +11897,7 @@ static int intel_crtc_atomic_check(struct drm_crtc *crtc,
 	}
 
 	if (mode_changed && !crtc_state->active)
-		pipe_config->wm_changed = true;
+		pipe_config->update_wm_post = true;
 
 	if (mode_changed && crtc_state->enable &&
 	    dev_priv->display.crtc_compute_clock &&
@@ -13442,12 +13451,12 @@ static bool needs_vblank_wait(struct intel_crtc_state *crtc_state)
 		return true;
 
 	/* wm changes, need vblank before final wm's */
-	if (crtc_state->wm_changed)
+	if (crtc_state->update_wm_post)
 		return true;
 
 	/*
 	 * cxsr is re-enabled after vblank.
-	 * This is already handled by crtc_state->wm_changed,
+	 * This is already handled by crtc_state->update_wm_post,
 	 * but added for clarity.
 	 */
 	if (crtc_state->disable_cxsr)

drivers/gpu/drm/i915/intel_drv.h

@@ -420,7 +420,7 @@ struct intel_crtc_state {
 
 	bool update_pipe; /* can a fast modeset be performed? */
 	bool disable_cxsr;
-	bool wm_changed; /* watermarks are updated */
+	bool update_wm_pre, update_wm_post; /* watermarks are updated */
 	bool fb_changed; /* fb on any of the planes is changed */
 
 	/* Pipe source size (ie. panel fitter input size)