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

[Chris Wilson]

On Mon, Jun 23, 2014 at 01:18:35PM +0000, Mateo Lozano, Oscar wrote:
> > -----Original Message-----
> > From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> > Sent: Monday, June 23, 2014 2:14 PM
> > To: Mateo Lozano, Oscar
> > Cc: Volkin, Bradley D; intel-gfx at lists.freedesktop.org
> > Subject: Re: [Intel-gfx] [PATCH 26/53] drm/i915/bdw: New logical ring
> > submission mechanism
> > 
> > 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.
> > -Chris
> 
> Sorry, Chris, I obviously don´t have the same experience with 915 you have: how do you propose to extract the right context from the ring?

The rings are a set of buffers and vfuncs that are associated with a
context. Before you can call intel_ring_begin() you must know what
context you want to operate on and therefore can pick the right
logical/legacy ring and interface for RCS/BCS/VCS/etc
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre