[PATCH] drm/amdgpu: fix drm panic null pointer when driver not support atomic

[yaolu]

From: Lu Yao <ya...@kylinos.cn>

When driver not support atomic, fb using plane->fb rather than
plane->state->fb.

Fixes: fe151ed7af54 ("drm/amdgpu: add generic display panic helper code")
Signed-off-by: Lu Yao <ya...@kylinos.cn>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_display.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
index b5d34797d606..52bc04452812 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c
@@ -1880,7 +1880,12 @@ int amdgpu_display_get_scanout_buffer(struct drm_plane 
*plane,
                                      struct drm_scanout_buffer *sb)
 {
        struct amdgpu_bo *abo;
-       struct drm_framebuffer *fb = plane->state->fb;
+       struct drm_framebuffer *fb;
+
+       if (drm_drv_uses_atomic_modeset(plane->dev))
+               fb = plane->state->fb;
+       else
+               fb = plane->fb;
 
        if (!fb)
                return -EINVAL;
-- 
2.25.1