drm/atomic: clear out fence when duplicating state

[Fixed differently in 4.10]

The fence needs to be cleared out, otherwise the following commit
might wait on a stale fence from the previous commit. This was fixed
as a side effect of 9626014258a5 (drm/fence: add in-fences support)
in kernel 4.10.

As this commit introduces new functionality and as such can not be
applied to stable, this patch is the minimal fix for the kernel 4.9
stable series.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 338766c64c990dd35fe0d1a0d0cd6ce1ad38c3ed..a05bb3891119102d4d96c48b7c9957353c7ae9ad 100644 (file)
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -3115,6 +3115,8 @@ void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
 
        if (state->fb)
                drm_framebuffer_reference(state->fb);
+
+       state->fence = NULL;
 }
 EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);