panfrost: Flush before compute jobs

Suboptimal but fixes KHR-GLES31.core.compute_shader.pipeline-post-xfb,
which is stubbornly still broken with memory barriers implemented and
cache flush jobs inserted. More investigation needed but probably not
right now.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11123>

src/gallium/drivers/panfrost/pan_compute.c

@@ -101,6 +101,11 @@ panfrost_launch_grid(struct pipe_context *pipe,
 {
         struct panfrost_context *ctx = pan_context(pipe);
         struct panfrost_device *dev = pan_device(pipe->screen);
+
+        /* XXX - shouldn't be necessary with working memory barriers. Affected
+         * test: KHR-GLES31.core.compute_shader.pipeline-post-xfb */
+        panfrost_flush_all_batches(ctx);
+
         struct panfrost_batch *batch = panfrost_get_batch_for_fbo(ctx);
 
         struct panfrost_shader_state *cs =