drm/radeon/kms: Don't try to enable IRQ if we have no handler installed

If for any reason we haven't installed handler we shouldn't try to
enable IRQ/MSI on the hw so we don't get unhandled IRQ/MSI which
makes the kernel sad.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index d2b789e..8760d66 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -131,7 +131,8 @@
 			break;
 		}
 	}
-	r100_irq_set(rdev);
+	if (rdev->irq.installed)
+		r100_irq_set(rdev);
 }
 
 void r100_hpd_fini(struct radeon_device *rdev)
@@ -243,6 +244,11 @@
 {
 	uint32_t tmp = 0;
 
+	if (!rdev->irq.installed) {
+		WARN(1, "Can't enable IRQ/MSI because no handler is installed.\n");
+		WREG32(R_000040_GEN_INT_CNTL, 0);
+		return -EINVAL;
+	}
 	if (rdev->irq.sw_int) {
 		tmp |= RADEON_SW_INT_ENABLE;
 	}