drm/radeon/kms: properly set accel working flag and bailout when false

If accel is not working many subsystem such as the ib pool might not be
initialized properly that can lead to segfault inside kernel when cs
ioctl is call with non working acceleration. To avoid this make sure
the accel working flag is false when an error in GPU startup happen and
return EBUSY from cs ioctl if accel is not working.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r520.c b/drivers/gpu/drm/radeon/r520.c
index 4ae1615..25084e8 100644
--- a/drivers/gpu/drm/radeon/r520.c
+++ b/drivers/gpu/drm/radeon/r520.c
@@ -218,6 +218,8 @@
 
 int r520_resume(struct radeon_device *rdev)
 {
+	int r;
+
 	/* Make sur GART are not working */
 	if (rdev->flags & RADEON_IS_PCIE)
 		rv370_pcie_gart_disable(rdev);
@@ -237,7 +239,11 @@
 	radeon_surface_init(rdev);
 
 	rdev->accel_working = true;
-	return r520_startup(rdev);
+	r = r520_startup(rdev);
+	if (r) {
+		rdev->accel_working = false;
+	}
+	return r;
 }
 
 int r520_init(struct radeon_device *rdev)