Re: [PATCH 4/6] drm/i915: Include engine state on detecting a missed breadcrumb/seqno

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

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

> Now that we have a common engine state pretty printer, we can use that
> instead of the adhoc information printed when we miss a breadcrumb.
>
> v2: Rearrange intel_engine_disarm_breadcrumbs() to avoid calling
> intel_engine_dump() under the rb spinlock (Mika) and to pretty-print the
> error state early so that we include the full list of waiters.
> v3: Pass missed breadcrumb msg to pretty-printer as the header
> v4: Preserve DRM_DEBUG_DRIVER filtering.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

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

> ---
>  drivers/gpu/drm/i915/intel_breadcrumbs.c | 25 ++++++++++++++-----------
>  drivers/gpu/drm/i915/intel_engine_cs.c   |  6 ++++++
>  2 files changed, 20 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> index 5ae2d276f7f3..24c6fefdd0b1 100644
> --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
> +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> @@ -64,12 +64,13 @@ static unsigned long wait_timeout(void)
>  
>  static noinline void missed_breadcrumb(struct intel_engine_cs *engine)
>  {
> -	DRM_DEBUG_DRIVER("%s missed breadcrumb at %pS, irq posted? %s, current seqno=%x, last=%x\n",
> -			 engine->name, __builtin_return_address(0),
> -			 yesno(test_bit(ENGINE_IRQ_BREADCRUMB,
> -					&engine->irq_posted)),
> -			 intel_engine_get_seqno(engine),
> -			 intel_engine_last_submit(engine));
> +	if (drm_debug & DRM_UT_DRIVER) {
> +		struct drm_printer p = drm_debug_printer(__func__);
> +
> +		intel_engine_dump(engine, &p,
> +				  "%s missed breadcrumb at %pS\n",
> +				  engine->name, __builtin_return_address(0));
> +	}
>  
>  	set_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings);
>  }
> @@ -213,28 +214,30 @@ void intel_engine_unpin_breadcrumbs_irq(struct intel_engine_cs *engine)
>  void intel_engine_disarm_breadcrumbs(struct intel_engine_cs *engine)
>  {
>  	struct intel_breadcrumbs *b = &engine->breadcrumbs;
> -	struct intel_wait *wait, *n, *first;
> +	struct intel_wait *wait, *n;
>  
>  	if (!b->irq_armed)
>  		return;
>  
> -	/* We only disarm the irq when we are idle (all requests completed),
> +	/*
> +	 * We only disarm the irq when we are idle (all requests completed),
>  	 * so if the bottom-half remains asleep, it missed the request
>  	 * completion.
>  	 */
> +	if (intel_engine_wakeup(engine) & ENGINE_WAKEUP_ASLEEP)
> +		missed_breadcrumb(engine);
>  
>  	spin_lock_irq(&b->rb_lock);
>  
>  	spin_lock(&b->irq_lock);
> -	first = fetch_and_zero(&b->irq_wait);
> +	b->irq_wait = NULL;
>  	if (b->irq_armed)
>  		__intel_engine_disarm_breadcrumbs(engine);
>  	spin_unlock(&b->irq_lock);
>  
>  	rbtree_postorder_for_each_entry_safe(wait, n, &b->waiters, node) {
>  		RB_CLEAR_NODE(&wait->node);
> -		if (wake_up_process(wait->tsk) && wait == first)
> -			missed_breadcrumb(engine);
> +		wake_up_process(wait->tsk);
>  	}
>  	b->waiters = RB_ROOT;
>  
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index e9d5cd28291f..aa490120749a 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1822,6 +1822,12 @@ void intel_engine_dump(struct intel_engine_cs *engine,
>  	}
>  	spin_unlock_irq(&b->rb_lock);
>  
> +	drm_printf(m, "IRQ? 0x%lx (breadcrumbs? %s) (execlists? %s)\n",
> +		   engine->irq_posted,
> +		   yesno(test_bit(ENGINE_IRQ_BREADCRUMB,
> +				  &engine->irq_posted)),
> +		   yesno(test_bit(ENGINE_IRQ_EXECLIST,
> +				  &engine->irq_posted)));
>  	drm_printf(m, "Idle? %s\n", yesno(intel_engine_is_idle(engine)));
>  	drm_printf(m, "\n");
>  }
> -- 
> 2.15.0
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