diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index 279801ca5110aff68d80ea452751d7f9b0bf748f..04f2514f756453bfdc7275a52c65549e631cfc6c 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;
 }