On Thu, Jul 11, 2024 at 04:28:53PM +0000, Cavitt, Jonathan wrote:
> -----Original Message-----
> From: Intel-gfx <intel-gfx-boun...@lists.freedesktop.org> On Behalf Of Nitin
> Gote
> Sent: Thursday, July 11, 2024 9:32 AM
> To: Wilson, Chris P <chris.p.wil...@intel.com>; tursu...@ursulin.net;
> intel-...@lists.freedesktop.org
> Cc: dri-devel@lists.freedesktop.org; Shyti, Andi <andi.sh...@intel.com>; Das,
> Nirmoy <nirmoy....@intel.com>; janusz.krzyszto...@linux.intel.com; Gote,
> Nitin R <nitin.r.g...@intel.com>; Chris Wilson
> <chris.p.wil...@linux.intel.com>; sta...@vger.kernel.org
> 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.cav...@intel.com>
> -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.sh...@intel.com>
> > Signed-off-by: Nitin Gote <nitin.r.g...@intel.com>
> > Cc: Chris Wilson <chris.p.wil...@linux.intel.com>
> > CC: <sta...@vger.kernel.org> # 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
> >
> >
