+ lockup->last_cp_rptr = cp->rptr;
+ lockup->last_jiffies = jiffies;
+}
+
+/**
+ * r100_gpu_cp_is_lockup() - check if CP is lockup by recording information
+ * @rdev: radeon device structure
+ * @lockup: r100_gpu_lockup structure holding CP lockup tracking informations
+ * @cp: radeon_cp structure holding CP information
+ *
+ * We don't need to initialize the lockup tracking information as we will either
+ * have CP rptr to a different value of jiffies wrap around which will force
+ * initialization of the lockup tracking informations.
+ *
+ * A possible false positivie is if we get call after while and last_cp_rptr ==
+ * the current CP rptr, even if it's unlikely it might happen. To avoid this
+ * if the elapsed time since last call is bigger than 2 second than we return
+ * false and update the tracking information. Due to this the caller must call
+ * r100_gpu_cp_is_lockup several time in less than 2sec for lockup to be reported
+ * the fencing code should be cautious about that.
+ *
+ * Caller should write to the ring to force CP to do something so we don't get
+ * false positive when CP is just gived nothing to do.
+ *
+ **/
+bool r100_gpu_cp_is_lockup(struct radeon_device *rdev, struct r100_gpu_lockup *lockup, struct radeon_cp *cp)
+{
+ unsigned long cjiffies, elapsed;
+
+ cjiffies = jiffies;
+ if (!time_after(cjiffies, lockup->last_jiffies)) {
+ /* likely a wrap around */
+ lockup->last_cp_rptr = cp->rptr;
+ lockup->last_jiffies = jiffies;
+ return false;
+ }
+ if (cp->rptr != lockup->last_cp_rptr) {
+ /* CP is still working no lockup */
+ lockup->last_cp_rptr = cp->rptr;
+ lockup->last_jiffies = jiffies;
+ return false;
+ }
+ elapsed = jiffies_to_msecs(cjiffies - lockup->last_jiffies);
+ if (elapsed >= 3000) {
+ /* very likely the improbable case where current
+ * rptr is equal to last recorded, a while ago, rptr
+ * this is more likely a false positive update tracking
+ * information which should force us to be recall at
+ * latter point
+ */
+ lockup->last_cp_rptr = cp->rptr;
+ lockup->last_jiffies = jiffies;
+ return false;
+ }
+ if (elapsed >= 1000) {
+ dev_err(rdev->dev, "GPU lockup CP stall for more than %lumsec\n", elapsed);
+ return true;
+ }
+ /* give a chance to the GPU ... */
+ return false;