drm/msm: add rd logging debugfs

To ease debugging, add debugfs file which can be cat/tail'd to log
submits, along with fence #.  If GPU hangs, you can look at 'gpu'
debugfs file to find last completed fence and current register state,
and compare with logged rd file to narrow down the DRAW_INDX which
triggered the GPU hang.

Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/msm_gpu.c

@@ -377,6 +377,10 @@ int msm_gpu_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit,
 
 	inactive_cancel(gpu);
 
+	msm_rd_dump_submit(submit);
+
+	gpu->submitted_fence = submit->fence;
+
 	ret = gpu->funcs->submit(gpu, submit, ctx);
 	priv->lastctx = ctx;