[Intel-gfx] [PATCH 26/53] drm/i915/bdw: New logical ring submission mechanism

[Daniel Vetter]

On Mon, Jun 23, 2014 at 02:13:55PM +0100, Chris Wilson wrote:
> On Mon, Jun 23, 2014 at 01:09:37PM +0000, Mateo Lozano, Oscar wrote:
> > So far, yes, but that´s only because I artificially made intel_lrc.c self-contained, as Daniel requested. What if we need to execute commands from somewhere else, like in intel_gen7_queue_flip()?
> > 
> > And this takes me to another discussion: this logical ring vs legacy ring split is probably a good idea (time will tell), but we should provide a way of sending commands for execution without knowing if Execlists are enabled or not. In the early series that was easy because we reused the ring_begin, ring_emit & ring_advance functions, but this is not the case anymore. And without this, sooner or later somebody will break legacy or execlists (this already happened last week, when somebody here was implementing native sync without knowing about Execlists).
> > 
> > So, the questions is: how do you feel about a dev_priv.gt vfunc that takes a context, a ring, an array of DWORDS and a BB length and does the intel_(logical)_ring_begin/emit/advance based on i915.enable_execlists?
> 
> I'm still baffled by the design. intel_ring_begin() and friends should
> be able to find their context (logical or legacy) from the ring and
> dtrt.

Well I'm opting for a the different approach of presuming that the callers
knows whether we're running with execlists or legacy rings and so will
have a clean (and full) split. If we really need to submit massive amounts
of cs commands from the kernel we should launch that as a batch, which
should be fairly unform for both legacy ring and execlists mode.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch