[Intel-gfx] [PATCH 4/8] drm/i915: Rename ctx->id to ctx->handle

[Daniel Vetter]

On Thu, Jul 03, 2014 at 12:01:35PM +0000, Mateo Lozano, Oscar wrote:
> > -----Original Message-----
> > From: Chris Wilson [mailto:chris at chris-wilson.co.uk]
> > Sent: Thursday, July 03, 2014 10:53 AM
> > To: Mateo Lozano, Oscar; intel-gfx at lists.freedesktop.org
> > Subject: Re: [Intel-gfx] [PATCH 4/8] drm/i915: Rename ctx->id to ctx->handle
> > 
> > On Thu, Jul 03, 2014 at 10:30:52AM +0100, Chris Wilson wrote:
> > > On Thu, Jun 26, 2014 at 02:24:15PM +0100, oscar.mateo at intel.com
> > wrote:
> > > > From: Oscar Mateo <oscar.mateo at intel.com>
> > > >
> > > > This is an Execlists preparatory patch, since they make context ID
> > > > become an overloaded term:
> > > >
> > > > - In the software, it was used to distinguish which context userspace was
> > > >   trying to use.
> > > > - In the BSpec, the term is used to describe the 20-bits long field the
> > > >   hardware uses to it to discriminate the contexts that are submitted to
> > > >   the ELSP and inform the driver about their current status (via Context
> > > >   Switch Interrupts and Context Status Buffers).
> > > >
> > > > Initially, I tried to make the different meanings converge, but it
> > > > proved
> > > > impossible:
> > > >
> > > > - The software ctx->id is per-filp, while the hardware one needs to be
> > > >   globally unique.
> > > > - Also, we multiplex several backing states objects per intel_context,
> > > >   and all of them need unique HW IDs.
> > > > - I tried adding a per-filp ID and then composing the HW context ID as:
> > > >   ctx->id + file_priv->id + ring->id, but the fact that the hardware only
> > > >   uses 20-bits means we have to artificially limit the number of filps or
> > > >   contexts the userspace can create.
> > > >
> > > > The ctx->handle bits are done with this Cocci patch (plus manual
> > > > frobbing of the struct declaration):
> > > >
> > > > 	@@
> > > > 	struct intel_context c;
> > > > 	@@
> > > > 	- (c).id
> > > > 	+ c.handle
> > > >
> > > > 	@@
> > > > 	struct intel_context *c;
> > > > 	@@
> > > > 	- (c)->id
> > > > 	+ c->handle
> > > >
> > > > Also, while we are at it,
> > s/DEFAULT_CONTEXT_ID/DEFAULT_CONTEXT_HANDLE.
> > > >
> > > > Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
> > >
> > > Let's go whole hog here and call it ctx->user_handle.
> 
> ACK
> 
> > And it's unsigned and only 32bits...
> 
> ACK, I´ll change the type to unit32_t

Aside when resending please pull in all the r-b tags from Jesse so that
lazy me has less hassle when merging this ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch