drm/i915: Increase the amount of defense before computing vblank timestamps

Reported-by: Chris Clayton <chris2553@googlemail.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index f0c87bd..98106b7 100644 (file)
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -274,24 +274,35 @@ int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,
        return ret;
 }
 
-int i915_get_vblank_timestamp(struct drm_device *dev, int crtc,
+int i915_get_vblank_timestamp(struct drm_device *dev, int pipe,
                              int *max_error,
                              struct timeval *vblank_time,
                              unsigned flags)
 {
-       struct drm_crtc *drmcrtc;
+       struct drm_i915_private *dev_priv = dev->dev_private;
+       struct drm_crtc *crtc;
 
-       if (crtc < 0 || crtc >= dev->num_crtcs) {
-               DRM_ERROR("Invalid crtc %d\n", crtc);
+       if (pipe < 0 || pipe >= dev_priv->num_pipe) {
+               DRM_ERROR("Invalid crtc %d\n", pipe);
                return -EINVAL;
        }
 
        /* Get drm_crtc to timestamp: */
-       drmcrtc = intel_get_crtc_for_pipe(dev, crtc);
+       crtc = intel_get_crtc_for_pipe(dev, pipe);
+       if (crtc == NULL) {
+               DRM_ERROR("Invalid crtc %d\n", pipe);
+               return -EINVAL;
+       }
+
+       if (!crtc->enabled) {
+               DRM_DEBUG_KMS("crtc %d is disabled\n", pipe);
+               return -EBUSY;
+       }
 
        /* Helper routine in DRM core does all the work: */
-       return drm_calc_vbltimestamp_from_scanoutpos(dev, crtc, max_error,
-                                                    vblank_time, flags, drmcrtc);
+       return drm_calc_vbltimestamp_from_scanoutpos(dev, pipe, max_error,
+                                                    vblank_time, flags,
+                                                    crtc);
 }
 
 /*