Re: [igt-dev] [Intel-gfx] [PATCH i-g-t] tests/i915: Skip gem_exec_fair on GuC based platforms

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Wed, 13 Oct 2021 18:07:05 -0700, John Harrison wrote:
>
> On 10/13/2021 15:53, Dixit, Ashutosh wrote:
> >> diff --git a/tests/i915/gem_exec_fair.c b/tests/i915/gem_exec_fair.c
> >> index ef5a450f6..ca9c73c6e 100644
> >> --- a/tests/i915/gem_exec_fair.c
> >> +++ b/tests/i915/gem_exec_fair.c
> >> @@ -1314,6 +1314,12 @@ igt_main
> >>		igt_require(gem_scheduler_enabled(i915));
> >>		igt_require(gem_scheduler_has_ctx_priority(i915));
> >>
> >> +		/*
> >> +		 * These tests are for a specific scheduling model which is
> >> +		 * not currently implemented by GuC. So skip on GuC platforms.
> >> +		 */
> >> +		igt_require(intel_gen(intel_get_drm_devid(i915)) < 12);
> > Probably a feature check rather than a version check is better? Can we use
> > say gem_has_guc_submission() instead?
> >
> > Though appears gem_has_guc_submission() only checks if guc submission is
> > available, not if it is actually in use (unless guc will used when
> > available automatically)? Is it possible to add the check if guc submission
> > is actually in use? Or a check for guc scheduler?
>
> I believe this has come up a few times before. My understanding is that no,
> there is no current official/safe way for userland to check if GuC
> submission is enabled (you can read some of the debugfs files and make an
> educated guess but that isn't exactly an official interface). And the
> answer was that it isn't worth adding a UAPI specifically for it. Not least
> because it would be a UAPI solely for use by IGT which is not allowed.

Hmm, so kernel will use GuC submission if bit 0 of enable_guc module param
is 1, correct? Which is what gem_has_guc_submission() checks, though I
guess we can also add a function gem_using_guc_submission() which is
basically an alias for gem_has_guc_submission(). So we can't do this? Or
the module param is not an acceptable uapi? But we already introduced
gem_has_guc_submission()?

I think this kind of a generation/version check should be implemented in
the kernel. If kernel wants to turn on GuC submission by default let it do
that and set enable_guc. In IGT we just check enable_guc. No? Thanks.