Re: [PATCH v2] drm/i915/tgl: Disable preemption while being debugged

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> We see failures where the context continues executing past a
> preemption event, eventually leading to situations where a request has
> executed before we have event submitted it to HW! It seems like tgl is
> ignoring our RING_TAIL updates, but more likely is that there is a
> missing update required for our semaphore waits around preemption.
>
> v2: And disable internal semaphore usage
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>

Acked-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_lrc.c | 3 +++
>  drivers/gpu/drm/i915/i915_pci.c     | 1 +
>  2 files changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index 47d766ccea71..a3f0e4999744 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -2939,6 +2939,9 @@ void intel_execlists_set_default_submission(struct intel_engine_cs *engine)
>  			engine->flags |= I915_ENGINE_HAS_PREEMPTION;
>  	}
>  
> +	if (INTEL_GEN(engine->i915) >= 12) /* XXX disabled for debugging */
> +		engine->flags &= ~I915_ENGINE_HAS_SEMAPHORES;
> +
>  	if (engine->class != COPY_ENGINE_CLASS && INTEL_GEN(engine->i915) >= 12)
>  		engine->flags |= I915_ENGINE_HAS_RELATIVE_MMIO;
>  }
> diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
> index b3cc8560696b..2ca34a5cf7d3 100644
> --- a/drivers/gpu/drm/i915/i915_pci.c
> +++ b/drivers/gpu/drm/i915/i915_pci.c
> @@ -798,6 +798,7 @@ static const struct intel_device_info intel_tigerlake_12_info = {
>  	.engine_mask =
>  		BIT(RCS0) | BIT(BCS0) | BIT(VECS0) | BIT(VCS0) | BIT(VCS2),
>  	.has_rc6 = false, /* XXX disabled for debugging */
> +	.has_logical_ring_preemption = false, /* XXX disabled for debugging */
>  };
>  
>  #undef GEN
> -- 
> 2.23.0
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