[Intel-gfx] [PATCH v3] drm/i915: Add null state batch to active list

[Volkin, Bradley D]

On Wed, May 21, 2014 at 07:02:56AM -0700, Mika Kuoppala wrote:
> +	if (ring->id == RCS && !to->is_initialized && from == NULL) {
> +		ret = i915_gem_render_state_init(ring);
> +		if (ret)
> +			DRM_ERROR("init render state: %d\n", ret);
> +	}

Apologies if this has already been discussed, but why do we have the
'from == NULL' check? Shouldn't we initialize all uninitialized RCS
contexts? Otherwise I thought we'll inherit whatever state 'from' left
behind.

The hw state should be valid in either case (and so I expect would fix
the rc6 issue either way), it's just the difference between initializing
every context to a specific valid state or initializing every context to
_some_ valid state. The commit message on the first render state patch
seemed to indicate the former while the implementation looks like the
latter. Just want to understand which we intended.

Thanks,
Brad