drm/radeon/kms: fix ring info in debugfs on r600+

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Acked-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/r600.c

@@ -2361,21 +2361,21 @@ static int r600_debugfs_cp_ring_info(struct seq_file *m, void *data)
 	struct drm_info_node *node = (struct drm_info_node *) m->private;
 	struct drm_device *dev = node->minor->dev;
 	struct radeon_device *rdev = dev->dev_private;
-	uint32_t rdp, wdp;
 	unsigned count, i, j;
 
 	radeon_ring_free_size(rdev);
-	rdp = RREG32(CP_RB_RPTR);
-	wdp = RREG32(CP_RB_WPTR);
-	count = (rdp + rdev->cp.ring_size - wdp) & rdev->cp.ptr_mask;
+	count = (rdev->cp.ring_size / 4) - rdev->cp.ring_free_dw;
 	seq_printf(m, "CP_STAT 0x%08x\n", RREG32(CP_STAT));
-	seq_printf(m, "CP_RB_WPTR 0x%08x\n", wdp);
-	seq_printf(m, "CP_RB_RPTR 0x%08x\n", rdp);
+	seq_printf(m, "CP_RB_WPTR 0x%08x\n", RREG32(CP_RB_WPTR));
+	seq_printf(m, "CP_RB_RPTR 0x%08x\n", RREG32(CP_RB_RPTR));
+	seq_printf(m, "driver's copy of the CP_RB_WPTR 0x%08x\n", rdev->cp.wptr);
+	seq_printf(m, "driver's copy of the CP_RB_RPTR 0x%08x\n", rdev->cp.rptr);
 	seq_printf(m, "%u free dwords in ring\n", rdev->cp.ring_free_dw);
 	seq_printf(m, "%u dwords in ring\n", count);
+	i = rdev->cp.rptr;
 	for (j = 0; j <= count; j++) {
-		i = (rdp + j) & rdev->cp.ptr_mask;
 		seq_printf(m, "r[%04d]=0x%08x\n", i, rdev->cp.ring[i]);
+		i = (i + 1) & rdev->cp.ptr_mask;
 	}
 	return 0;
 }