[Intel-gfx] [PATCH 18/22] drm/i915: Forgo last_fence active request tracking

[Matthew Auld]

On 17/06/2019 08:19, Chris Wilson wrote:
> We were using the last_fence to track the last request that used this
> vma that might be interpreted by a fence register and forced ourselves
> to wait for this request before modifying any fence register that
> overlapped our vma. Due to requirement that we need to track any XY_BLT
> command, linear or tiled, this in effect meant that we have to track the
> vma for its active lifespan anyway, so we can forgo the explicit
> last_fence tracking and just use the whole vma->active.
> 
> Another solution would be to pipeline the register updates, and would
> help resolve some long running stalls for gen3 (but only gen 2 and 3!)
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld at intel.com>