[Intel-gfx] [PATCH libdrm 15/15] intel: Support passing of explicit fencing from execbuf

[Rafael Antognolli]

Hi Chris,

On Thu, Aug 25, 2016 at 10:08:33AM +0100, Chris Wilson wrote:
> Allow the caller to pass in an fd to an array of fences to control
> serialisation of the execbuf in the kernel and on the GPU, and in return
> allow creation of a fence fd for signaling the completion (and flushing)
> of the batch. When the returned fence is signaled, all writes to the
> buffers inside the batch will be complete and coherent from the cpu, or
> other consumers. The return fence is a sync_file object and can be
> passed to other users (such as atomic modesetting, or other drivers).
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  intel/intel_bufmgr.h     |  6 ++++++
>  intel/intel_bufmgr_gem.c | 38 +++++++++++++++++++++++++++++++++-----
>  2 files changed, 39 insertions(+), 5 deletions(-)
> 
> diff --git a/intel/intel_bufmgr_gem.c b/intel/intel_bufmgr_gem.c
> index 259543f..02ec757 100644
> --- a/intel/intel_bufmgr_gem.c
> +++ b/intel/intel_bufmgr_gem.c
> @@ -2412,13 +2419,20 @@ do_exec2(drm_intel_bo *bo, int used, drm_intel_context *ctx,
>  		i915_execbuffer2_set_context_id(execbuf, 0);
>  	else
>  		i915_execbuffer2_set_context_id(execbuf, ctx->ctx_id);
> -	execbuf.rsvd2 = 0;
> +	if (in_fence != -1) {
> +		execbuf.rsvd2 = in_fence;
> +		flags |= I915_EXEC_FENCE_IN;

The flags are being set here, but not really used anywhere.
Maybe you meant something like:

execbuf.flags != I915_EXEC_FENCE_IN;

?

> +	if (out_fence != NULL) {
> +		*out_fence = -1;
> +		flags |= I915_EXEC_FENCE_OUT;
> +	}

Same as above.

Regards,
Rafael