[igt-dev] [PATCH i-g-t 3/4] lib/igt_gt: Add compute engine

[Zbigniew Kempczyński]

On Thu, Oct 21, 2021 at 05:29:50PM -0700, Dixit, Ashutosh wrote:
> On Thu, 21 Oct 2021 17:12:26 -0700, Dixit, Ashutosh wrote:
> >
> > On Thu, 21 Oct 2021 00:33:21 -0700, Zbigniew Kempczyński wrote:
> > >
> > > On Thu, Oct 21, 2021 at 10:05:07AM +0530, priyanka.dandamudi at intel.com wrote:
> > > > From: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
> > > >
> > > > Add compute (CCS) engine. Add this to the IGT
> > > > structure to allow gem tests to execute.
> > > >
> > > > Signed-off-by: Stuart Summers <stuart.summers at intel.com>
> > > > Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
> > > > Signed-off-by: Priyanka Dandamudi <priyanka.dandamudi at intel.com>
> > > > Cc: Ashutosh Dixit <ashutosh.dixit at intel.com>
> > > > Cc: Arjun Melkaveri <arjun.melkaveri at intel.com>
> > > > ---
> > > >  lib/igt_gt.c | 4 ++++
> > > >  1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/lib/igt_gt.c b/lib/igt_gt.c
> > > > index a0ba04cc..80fb65ca 100644
> > > > --- a/lib/igt_gt.c
> > > > +++ b/lib/igt_gt.c
> > > > @@ -604,6 +604,10 @@ const struct intel_execution_engine2 intel_execution_engines2[] = {
> > > >	{ "vcs1", I915_ENGINE_CLASS_VIDEO, 1, I915_EXEC_BSD | I915_EXEC_BSD_RING2 },
> > > >	{ "vcs2", I915_ENGINE_CLASS_VIDEO, 2, -1 },
> > > >	{ "vecs0", I915_ENGINE_CLASS_VIDEO_ENHANCE, 0, I915_EXEC_VEBOX },
> > > > +	{ "ccs0", I915_ENGINE_CLASS_COMPUTE, 0 , -1},
> > > > +	{ "ccs1", I915_ENGINE_CLASS_COMPUTE, 1 , -1},
> > > > +	{ "ccs2", I915_ENGINE_CLASS_COMPUTE, 2 , -1},
> > > > +	{ "ccs3", I915_ENGINE_CLASS_COMPUTE, 3 , -1},
> >
> > Is this correct? Isn't intel_execution_engines2 a list of just the legacy
> > engines? I don't think compute engines (which may vary in number) can be
> > added to the list of legacy engines. Isn't it true that compute engines can
> > only be accessed by querying the present engines dynamically (using
> > something like intel_ctx_create_all_physical())?
> 
> I've copied Tvrtko (the boss :), but I am pretty sure what I said is
> correct. Legacy engines are what context 0 is created with (without adding
> any more engines onto context 0). So unless we can confirm that these
> engines are present for context 0 in the kernel we can't add them in IGT.

I'm sorry, you're right. I wasn't aware legacy engines are "frozen", so
context 0 won't get an access to ccs. My r-b is incorrect then and patch
shouldn't land.  Another problem you've just realized me is with above
patch I would still need to detect ccs somehow on context 0 depending
on gen to allow iterator to go over existing engines.

--
Zbigniew