[Intel-gfx] [PATCH] drm/i915/guc: Check that the breadcrumb irq is enabled

[Chris Wilson]

Quoting Chris Wilson (2018-04-09 15:49:22)
> Quoting Michal Wajdeczko (2018-04-09 15:08:40)
> > On Mon, 09 Apr 2018 14:42:19 +0200, Chris Wilson  
> > <chris at chris-wilson.co.uk> wrote:
> > 
> > > Our execlists emulation for GuC requires use of the breadcrumb following
> > > every request as a simulcrum for the context-switch interrupt, which we
> > > then use to drive the submission tasklet. Therefore, when we unpark the
> > > engine for use with the GuC, we pin the breadcrumb interrupt to keep it
> > > enabled for the duration. This has to be remain so across all resets,
> > > wedging and resume, so check we do have the irq enabled when we start
> > > submitting requests to the GuC and on all submissions thereafter.
> > >
> > > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > > Cc: Michał Winiarski <michal.winiarski at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_guc_submission.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c  
> > > b/drivers/gpu/drm/i915/intel_guc_submission.c
> > > index 97121230656c..a7957b669b68 100644
> > > --- a/drivers/gpu/drm/i915/intel_guc_submission.c
> > > +++ b/drivers/gpu/drm/i915/intel_guc_submission.c
> > > @@ -758,6 +758,8 @@ static void guc_submission_tasklet(unsigned long  
> > > data)
> > >       struct execlist_port *port = execlists->port;
> > >       struct i915_request *rq;
> > > +     GEM_BUG_ON(!READ_ONCE(engine->breadcrumbs.irq_enabled));
> > > +
> > >       rq = port_request(port);
> > >       while (rq && i915_request_completed(rq)) {
> > >               trace_i915_request_out(rq);
> > 
> > LGTM, but can you run this with GuC enabled ?
> 
> Are you afraid? If gem_eio isn't hitting this, I need to tweak gem_eio
> ;)

That run confirms that the existing test coverage is enough to hit this
error - the same tests we know are broken atm due to the unbalance this
is detecting.
-Chris