drm/nouveau/pm: fix oops if chipset has no pm support at all

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

diff --git a/drivers/gpu/drm/nouveau/nouveau_pm.c b/drivers/gpu/drm/nouveau/nouveau_pm.c
index dcc1692..34d591b 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_pm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_pm.c
@@ -284,9 +284,11 @@ nouveau_pm_perflvl_get(struct drm_device *dev, struct nouveau_pm_level *perflvl)
 
        memset(perflvl, 0, sizeof(*perflvl));
 
-       ret = pm->clocks_get(dev, perflvl);
-       if (ret)
-               return ret;
+       if (pm->clocks_get) {
+               ret = pm->clocks_get(dev, perflvl);
+               if (ret)
+                       return ret;
+       }
 
        if (pm->voltage.supported && pm->voltage_get) {
                ret = pm->voltage_get(dev);