[Intel-gfx] [PATCH] drm/i915/gt: Only disable powergating around rcs activity

[Eero Tamminen]

Hi,

According to quick testing I did, this clearly helps with low-power 
Media transcoding on BXT, and a bit on some other cases both on BXT & 
KBL GT3e.

However, it also seems to regress some cases.  They have too much 
variance to say for sure though (and because I can't build exactly same 
commit due to drm-tip getting rebased all the time).

Cases that may have regressed are similar to low-power ones, just using 
MediaSDK sample application and compute for encoding. For example:
sample_multi_transcode -i::h264 720x480p_30.00_4mb_h264_cabac_180s.264 
-o::h264 output.h264 -b 2000 -u 4 -n 4800 -async 4 -hw

(Chris, MediaSDK build installs sample_multi_transcode to 
share/mfx/samples/ directory.)


	- Eero

On 19.12.2019 18.45, Chris Wilson wrote:
> References: https://gitlab.freedesktop.org/drm/intel/issues/846
> Cc: Imre Deak <imre.deak at intel.com>
> Cc: Eero Tamminen <eero.t.tamminen at intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_engine_pm.c |  4 ++
>   drivers/gpu/drm/i915/gt/intel_rc6.c       | 46 +++++++++++++++++++----
>   drivers/gpu/drm/i915/gt/intel_rc6.h       |  3 ++
>   drivers/gpu/drm/i915/gt/intel_rc6_types.h |  6 +++
>   4 files changed, 52 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> index 8fb7b34fc5a6..1886d604f1ad 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
> @@ -36,6 +36,8 @@ static int __engine_unpark(struct intel_wakeref *wf)
>   	if (engine->unpark)
>   		engine->unpark(engine);
>   
> +	intel_rc6_unpark_engine(&engine->gt->rc6, engine);
> +
>   	intel_engine_unpark_heartbeat(engine);
>   	return 0;
>   }
> @@ -232,6 +234,8 @@ static int __engine_park(struct intel_wakeref *wf)
>   	intel_engine_disarm_breadcrumbs(engine);
>   	intel_engine_pool_park(&engine->pool);
>   
> +	intel_rc6_park_engine(&engine->gt->rc6, engine);
> +
>   	/* Must be reset upon idling, or we may miss the busy wakeup. */
>   	GEM_BUG_ON(engine->execlists.queue_priority_hint != INT_MIN);
>   
> diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c
> index 9e303c29d6e3..7024c34917a2 100644
> --- a/drivers/gpu/drm/i915/gt/intel_rc6.c
> +++ b/drivers/gpu/drm/i915/gt/intel_rc6.c
> @@ -175,13 +175,7 @@ static void gen9_rc6_enable(struct intel_rc6 *rc6)
>   		GEN6_RC_CTL_RC6_ENABLE |
>   		rc6_mode;
>   
> -	/*
> -	 * WaRsDisableCoarsePowerGating:skl,cnl
> -	 *   - Render/Media PG need to be disabled with RC6.
> -	 */
> -	if (!NEEDS_WaRsDisableCoarsePowerGating(rc6_to_i915(rc6)))
> -		set(uncore, GEN9_PG_ENABLE,
> -		    GEN9_RENDER_PG_ENABLE | GEN9_MEDIA_PG_ENABLE);
> +	rc6->engines[RENDER_CLASS].pg_enable = GEN9_RENDER_PG_ENABLE | GEN9_MEDIA_PG_ENABLE;
>   }
>   
>   static void gen8_rc6_enable(struct intel_rc6 *rc6)
> @@ -601,6 +595,44 @@ void intel_rc6_unpark(struct intel_rc6 *rc6)
>   	set(uncore, GEN6_RC_CONTROL, rc6->ctl_enable);
>   }
>   
> +void intel_rc6_unpark_engine(struct intel_rc6 *rc6, struct intel_engine_cs *engine)
> +{
> +	struct intel_uncore *uncore = rc6_to_uncore(rc6);
> +	struct intel_pg_engine *e = &rc6->engines[engine->class];
> +
> +	if (!rc6->enabled)
> +		return;
> +
> +	if (!e->pg_enable)
> +		return;
> +
> +	spin_lock_irq(&uncore->lock);
> +	if (!e->active++) {
> +		rc6->pg_enable &= ~e->pg_enable;
> +		set(uncore, GEN9_PG_ENABLE, rc6->pg_enable);
> +	}
> +	spin_unlock_irq(&uncore->lock);
> +}
> +
> +void intel_rc6_park_engine(struct intel_rc6 *rc6, struct intel_engine_cs *engine)
> +{
> +	struct intel_uncore *uncore = rc6_to_uncore(rc6);
> +	struct intel_pg_engine *e = &rc6->engines[engine->class];
> +
> +	if (!rc6->enabled)
> +		return;
> +
> +	if (!e->pg_enable)
> +		return;
> +
> +	spin_lock_irq(&uncore->lock);
> +	if (e->active > 0 && !--e->active) {
> +		rc6->pg_enable |= e->pg_enable;
> +		set(uncore, GEN9_PG_ENABLE, rc6->pg_enable);
> +	}
> +	spin_unlock_irq(&uncore->lock);
> +}
> +
>   void intel_rc6_park(struct intel_rc6 *rc6)
>   {
>   	struct intel_uncore *uncore = rc6_to_uncore(rc6);
> diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.h b/drivers/gpu/drm/i915/gt/intel_rc6.h
> index 9f0f23fca8af..d4e422038866 100644
> --- a/drivers/gpu/drm/i915/gt/intel_rc6.h
> +++ b/drivers/gpu/drm/i915/gt/intel_rc6.h
> @@ -18,6 +18,9 @@ void intel_rc6_fini(struct intel_rc6 *rc6);
>   void intel_rc6_unpark(struct intel_rc6 *rc6);
>   void intel_rc6_park(struct intel_rc6 *rc6);
>   
> +void intel_rc6_unpark_engine(struct intel_rc6 *rc6, struct intel_engine_cs *engine);
> +void intel_rc6_park_engine(struct intel_rc6 *rc6, struct intel_engine_cs *engine);
> +
>   void intel_rc6_sanitize(struct intel_rc6 *rc6);
>   void intel_rc6_enable(struct intel_rc6 *rc6);
>   void intel_rc6_disable(struct intel_rc6 *rc6);
> diff --git a/drivers/gpu/drm/i915/gt/intel_rc6_types.h b/drivers/gpu/drm/i915/gt/intel_rc6_types.h
> index bfbb623f7a4f..e6fce9e7b34e 100644
> --- a/drivers/gpu/drm/i915/gt/intel_rc6_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_rc6_types.h
> @@ -22,6 +22,12 @@ struct intel_rc6 {
>   
>   	struct drm_i915_gem_object *pctx;
>   
> +	u32 pg_enable;
> +	struct intel_pg_engine {
> +		unsigned int active;
> +		u32 pg_enable;
> +	} engines[4];
> +
>   	bool supported : 1;
>   	bool enabled : 1;
>   	bool manual : 1;
>