[PATCH] drm/atomic: fix null pointer access to mode_fixup callback

[Inki Dae]

This patch fixes null pointer access incurred when
encoder driver didn't set its own mode_fixup callback.

mode_fixup callback shoudn't be called if the callback
of drm_encoder_helper_funcs is NULL.

Signed-off-by: Inki Dae <inki.dae at samsung.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c 
b/drivers/gpu/drm/drm_atomic_helper.c
index 5b59d5ad..b69469c 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -299,6 +299,9 @@ mode_fixup(struct drm_atomic_state *state)
                                return ret;
                        }
                } else {
+                       if (!funcs->mode_fixup)
+                               continue;
+
                        ret = funcs->mode_fixup(encoder, &crtc_state->mode,
                                                &crtc_state->adjusted_mode);
                        if (!ret) {
-- 
1.9.1