[Intel-gfx] [PATCH] drm/i915/pmu: Clear the previous sample value when parking

[Tvrtko Ursulin]

On 23/11/2017 00:06, Chris Wilson wrote:
> When turning off the engines, and the pmu sampling, clear the previous
> value as the current measurement should be 0.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>   drivers/gpu/drm/i915/i915_pmu.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index f1e932a3fb85..6f1316f5039a 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -135,9 +135,18 @@ static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
>   
>   void i915_pmu_gt_parked(struct drm_i915_private *i915)
>   {
> +	struct intel_engine_cs *engine;
> +	enum intel_engine_id id;
> +
>   	if (!i915->pmu.base.event_init)
>   		return;
>   
> +	for_each_engine(engine, i915, id) {
> +		engine->pmu.sample[I915_SAMPLE_BUSY].prev = 0;
> +		engine->pmu.sample[I915_SAMPLE_WAIT].prev = 0;
> +		engine->pmu.sample[I915_SAMPLE_SEMA].prev = 0;
> +	}
> +
>   	spin_lock_irq(&i915->pmu.lock);
>   	/*
>   	 * Signal sampling timer to stop if only engine events are enabled and
> 

Yes, this is indeed required.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Mind if I change it to use a loop to I915_ENGINE_SAMPLE_MAX, and then 
follow up with a patch which moves this define from uapi to i915_pmu.h? 
Since during engine classes we realized "/* non-ABI */" enums do not 
make sense in the uapi?

Regards,

Tvrtko