Re: [PATCH] drm/i915/selftests: Verify whitelist of context registers

From: Chris Wilson <chris@chris-wilson.co.uk>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
	intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915/selftests: Verify whitelist of context registers
Date: Wed, 24 Apr 2019 12:03:52 +0100	[thread overview]
Message-ID: <155610383229.19502.12508638103825220969@skylake-alporthouse-com> (raw)
In-Reply-To: <155610000320.19502.11596492856166711018@skylake-alporthouse-com>

Quoting Chris Wilson (2019-04-24 11:00:03)
> Quoting Tvrtko Ursulin (2019-04-16 15:50:27)
> > 
> > On 16/04/2019 10:12, Chris Wilson wrote:
> > > +     rq = ERR_PTR(-ENODEV);
> > > +     with_intel_runtime_pm(engine->i915, wakeref)
> > > +             rq = i915_request_alloc(engine, ctx);
> > > +     if (IS_ERR(rq))
> > > +             goto err_unpin;
> > > +
> > > +     if (engine->emit_init_breadcrumb) { /* Be nice if we hang */
> > > +             err = engine->emit_init_breadcrumb(rq);
> > > +             if (err)
> > > +                     goto err_request;
> > > +     }
> > > +
> > > +     err = engine->emit_bb_start(rq, batch->node.start, 0, 0);
> > 
> > Why is batch needed here when everything else is happy to run from the ring?
> 
> Because we are playing with HW registers, I want reset to work safely.
> So long as we have init_breadcrumb, the payload scrubbing should work.
> Ok.

No, I am an idiot. The batch is so that we emulate userspace with
unprivileged execution
-Chris
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