[PATCH] drm/i915: Treat crtc->mode.clock == 0 as disabled

[Chris Wilson]

Prevent a divide-by-zero by consistently treating an 'active' CRTC
without a mode set as actually disabled.
---
 drivers/gpu/drm/i915/intel_pm.c |   22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index e6f54ff..c929a4e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -44,6 +44,11 @@
  * i915.i915_enable_fbc parameter
  */
 
+static bool intel_crtc_active(struct drm_crtc *crtc)
+{
+	return to_intel_crtc(crtc)->active && crtc->fb && crtc->mode.clock;
+}
+
 static void i8xx_disable_fbc(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -405,9 +410,8 @@ void intel_update_fbc(struct drm_device *dev)
 	 *   - going to an unsupported config (interlace, pixel multiply, etc.)
 	 */
 	list_for_each_entry(tmp_crtc, &dev->mode_config.crtc_list, head) {
-		if (to_intel_crtc(tmp_crtc)->active &&
-		    !to_intel_crtc(tmp_crtc)->primary_disabled &&
-		    tmp_crtc->fb) {
+		if (intel_crtc_active(tmp_crtc) &&
+		    !to_intel_crtc(tmp_crtc)->primary_disabled) {
 			if (crtc) {
 				DRM_DEBUG_KMS("more than one pipe active, disabling compression\n");
 				dev_priv->no_fbc_reason = FBC_MULTIPLE_PIPES;
@@ -992,7 +996,7 @@ static struct drm_crtc *single_enabled_crtc(struct drm_device *dev)
 	struct drm_crtc *crtc, *enabled = NULL;
 
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
-		if (to_intel_crtc(crtc)->active && crtc->fb) {
+		if (intel_crtc_active(crtc)) {
 			if (enabled)
 				return NULL;
 			enabled = crtc;
@@ -1086,7 +1090,7 @@ static bool g4x_compute_wm0(struct drm_device *dev,
 	int entries, tlb_miss;
 
 	crtc = intel_get_crtc_for_plane(dev, plane);
-	if (crtc->fb == NULL || !to_intel_crtc(crtc)->active) {
+	if (!intel_crtc_active(crtc)) {
 		*cursor_wm = cursor->guard_size;
 		*plane_wm = display->guard_size;
 		return false;
@@ -1215,7 +1219,7 @@ static bool vlv_compute_drain_latency(struct drm_device *dev,
 	int entries;
 
 	crtc = intel_get_crtc_for_plane(dev, plane);
-	if (crtc->fb == NULL || !to_intel_crtc(crtc)->active)
+	if (!intel_crtc_active(crtc))
 		return false;
 
 	clock = crtc->mode.clock;	/* VESA DOT Clock */
@@ -1476,7 +1480,7 @@ static void i9xx_update_wm(struct drm_device *dev)
 
 	fifo_size = dev_priv->display.get_fifo_size(dev, 0);
 	crtc = intel_get_crtc_for_plane(dev, 0);
-	if (to_intel_crtc(crtc)->active && crtc->fb) {
+	if (intel_crtc_active(crtc)) {
 		int cpp = crtc->fb->bits_per_pixel / 8;
 		if (IS_GEN2(dev))
 			cpp = 4;
@@ -1490,7 +1494,7 @@ static void i9xx_update_wm(struct drm_device *dev)
 
 	fifo_size = dev_priv->display.get_fifo_size(dev, 1);
 	crtc = intel_get_crtc_for_plane(dev, 1);
-	if (to_intel_crtc(crtc)->active && crtc->fb) {
+	if (intel_crtc_active(crtc)) {
 		int cpp = crtc->fb->bits_per_pixel / 8;
 		if (IS_GEN2(dev))
 			cpp = 4;
@@ -2044,7 +2048,7 @@ sandybridge_compute_sprite_wm(struct drm_device *dev, int plane,
 	int entries, tlb_miss;
 
 	crtc = intel_get_crtc_for_plane(dev, plane);
-	if (crtc->fb == NULL || !to_intel_crtc(crtc)->active) {
+	if (!intel_crtc_active(crtc)) {
 		*sprite_wm = display->guard_size;
 		return false;
 	}
-- 
1.7.10.4

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