On Thu, Jul 11, 2024 at 04:28:53PM +0000, Cavitt, Jonathan wrote:
> -----Original Message-----
> From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of Nitin Gote
> Sent: Thursday, July 11, 2024 9:32 AM
> To: Wilson, Chris P <chris.p.wilson@xxxxxxxxx>; tursulin@xxxxxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx; Shyti, Andi <andi.shyti@xxxxxxxxx>; Das, Nirmoy <nirmoy.das@xxxxxxxxx>; janusz.krzysztofik@xxxxxxxxxxxxxxx; Gote, Nitin R <nitin.r.gote@xxxxxxxxx>; Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>; stable@xxxxxxxxxxxxxxx
> Subject: [PATCH v3] drm/i915/gt: Do not consider preemption during execlists_dequeue for gen8
> >
> > We're seeing a GPU HANG issue on a CHV platform, which was caused by
> > bac24f59f454 ("drm/i915/execlists: Enable coarse preemption boundaries for gen8").
> >
> > Gen8 platform has only timeslice and doesn't support a preemption mechanism
> > as engines do not have a preemption timer and doesn't send an irq if the
> > preemption timeout expires.
>
> That seems to mean the original can_preempt function was inaccurately built,
> so fixing it here makes the most sense to me, especially if it's causing problems.
>
> Reviewed-by: Jonathan Cavitt <jonathan.cavitt@xxxxxxxxx>
> -Jonathan Cavitt
>
> > So, add a fix to not consider preemption
> > during dequeuing for gen8 platforms.
> >
> > v2: Simplify can_preempt() function (Tvrtko Ursulin)
> >
> > v3:
> > - Inside need_preempt(), condition of can_preempt() is not required
> > as simplified can_preempt() is enough. (Chris Wilson)
> >
> > Fixes: bac24f59f454 ("drm/i915/execlists: Enable coarse preemption boundaries for gen8")
Something strange in here...
This patch is not using directly or indirectly (I915_ENGINE_HAS_PREEMPTION) the
can_preempt()...
> > Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11396
> > Suggested-by: Andi Shyti <andi.shyti@xxxxxxxxx>
> > Signed-off-by: Nitin Gote <nitin.r.gote@xxxxxxxxx>
> > Cc: Chris Wilson <chris.p.wilson@xxxxxxxxxxxxxxx>
> > CC: <stable@xxxxxxxxxxxxxxx> # v5.2+
> > ---
> > drivers/gpu/drm/i915/gt/intel_execlists_submission.c | 6 +-----
> > 1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > index 21829439e686..72090f52fb85 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_execlists_submission.c
> > @@ -3315,11 +3315,7 @@ static void remove_from_engine(struct i915_request *rq)
> >
> > static bool can_preempt(struct intel_engine_cs *engine)
> > {
> > - if (GRAPHICS_VER(engine->i915) > 8)
> > - return true;
> > -
> > - /* GPGPU on bdw requires extra w/a; not implemented */
> > - return engine->class != RENDER_CLASS;
> > + return GRAPHICS_VER(engine->i915) > 8;
> > }
> >
> > static void kick_execlists(const struct i915_request *rq, int prio)
> > --
> > 2.25.1
> >
> >
