gallium: pipe: add get_decoder_fence vfunc

Add a get_decoder_fence vfunc that can be used to query the status
of the previous decode job denoted by 'fence' given 'timeout'.

A pointer to a fence pointer can be  passed to the codecs before the
end_frame vfunc and the codec should then be responsible for allocating
a fence on command stream submission.

Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Boyuan Zhang <Boyuan.Zhang@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20133>

src/gallium/include/pipe/p_video_codec.h

@@ -119,6 +119,20 @@ struct pipe_video_codec
     * get encoder feedback
     */
    void (*get_feedback)(struct pipe_video_codec *codec, void *feedback, unsigned *size);
+
+   /**
+    * Get decoder fence.
+    *
+    * Can be used to query the status of the previous decode job denoted by
+    * 'fence' given 'timeout'.
+    *
+    * A pointer to a fence pointer can be passed to the codecs before the
+    * end_frame vfunc and the codec should then be responsible for allocating a
+    * fence on command stream submission.
+    */
+   int (*get_decoder_fence)(struct pipe_video_codec *codec,
+                            struct pipe_fence_handle *fence,
+                            uint64_t timeout);
 };
 
 /**

src/gallium/include/pipe/p_video_state.h

@@ -166,6 +166,8 @@ struct pipe_picture_desc
    uint32_t key_size;
    enum pipe_format input_format;
    enum pipe_format output_format;
+   /* A fence used on PIPE_VIDEO_ENTRYPOINT_DECODE to signal job completion */
+   struct pipe_fence_handle **fence;
 };
 
 struct pipe_quant_matrix