diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index cdf6e2149539..a959cc1e7c8e 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -728,6 +728,10 @@ int r100_irq_set(struct radeon_device *rdev)
 		tmp |= RADEON_FP2_DETECT_MASK;
 	}
 	WREG32(RADEON_GEN_INT_CNTL, tmp);
+
+	/* read back to post the write */
+	RREG32(RADEON_GEN_INT_CNTL);
+
 	return 0;
 }