[Mesa-dev] [PATCH] i965: Remove redundant gen check

[Kenneth Graunke]

On Thursday, April 09, 2015 07:46:34 PM Ben Widawsky wrote:
> The blit ring doesn't exist until Gen6, therefore we don't need to actually
> check it. Keep an assert to make sure old code doesn't do stupid stuff.
> 
> (Only compile tested)
> 
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  src/mesa/drivers/dri/i965/intel_batchbuffer.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/src/mesa/drivers/dri/i965/intel_batchbuffer.c b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
> index e522e4e..ada5573 100644
> --- a/src/mesa/drivers/dri/i965/intel_batchbuffer.c
> +++ b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
> @@ -702,7 +702,8 @@ intel_emit_post_sync_nonzero_flush(struct brw_context *brw)
>  void
>  intel_batchbuffer_emit_mi_flush(struct brw_context *brw)
>  {
> -   if (brw->batch.ring == BLT_RING && brw->gen >= 6) {
> +   if (brw->batch.ring == BLT_RING) {
> +      assert(brw->gen >= 6);
>        BEGIN_BATCH_BLT(4);
>        OUT_BATCH(MI_FLUSH_DW);
>        OUT_BATCH(0);
> 

NAK.  It doesn't work that way.

BEGIN_BATCH() sets brw->batch.ring to RENDER_RING.
BEGIN_BATCH_BLT() sets brw->batch.ring to BLT_RING.

This happens on all generations.  When doing execbuf, we ignore the ring
type on Gen4-5, and always use I915_EXEC_RENDER.  On Gen6+, we use both.

On Gen6+, we flush the batch when changing ring types.  On Gen4-5, we
don't care - it just reflects the type of commands emitted last.

I suppose we could change BEGIN_BATCH_BLT to use RENDER_RING for
everything on Gen4-5, so the ring enum matches up better.  That would
be fine.

As is, this will assert fail on Gen4-5.
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