-----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")
> 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
>
>
