Re: [PATCH v2 3/3] drm/i915: Defer declaration of missed-interrupt until the waiter is asleep

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

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

> If the waiter was currently running, assume it hasn't had a chance
> to process the pending interupt (e.g, low priority task on a loaded
> system) and wait until it sleeps before declaring a missed interrupt.
>
> References: https://bugs.freedesktop.org/show_bug.cgi?id=99816
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_breadcrumbs.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_breadcrumbs.c b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> index 4395b177493e..2ad29fb77b2d 100644
> --- a/drivers/gpu/drm/i915/intel_breadcrumbs.c
> +++ b/drivers/gpu/drm/i915/intel_breadcrumbs.c
> @@ -45,6 +45,15 @@ static void intel_breadcrumbs_hangcheck(unsigned long data)
>  		return;
>  	}
>  
> +	/* If the waiter was currently running, assume it hasn't had a chance
> +	 * to process the pending interupt (e.g, low priority task on a loaded
> +	 * system) and wait until it sleeps before declaring a missed interrupt.
> +	 */
> +	if (!intel_engine_wakeup(engine)) {

But this will happen if there is waiter running, or that there is
no waiter at all.

Don't we need to exclude the latter?

-Mika


> +		mod_timer(&b->hangcheck, wait_timeout());
> +		return;
> +	}
> +
>  	DRM_DEBUG("Hangcheck timer elapsed... %s idle\n", engine->name);
>  	set_bit(engine->id, &engine->i915->gpu_error.missed_irq_rings);
>  	mod_timer(&engine->breadcrumbs.fake_irq, jiffies + 1);
> -- 
> 2.11.0
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