[Intel-gfx] [PATCH] drm/i915: Move the decision to use the breadcrumb tasklet to the backend

[Chris Wilson]

Quoting Chris Wilson (2019-03-29 15:49:12)
> Use the engine->flags to store whether we want to kick the submission
> tasklet on receipt of a breadcrumb interrupt, so that this decision can
> be made by the submission backend and not dependent on a limited feature
> test within the interrupt handler. This should make it easier to adapt
> different submission backends.

This comes with a cherry on top!

add/remove: 0/1 grow/shrink: 2/2 up/down: 20/-86 (-66)
Function                                     old     new   delta
guc_submission_park                            5      18     +13
guc_submission_unpark                          5      12      +7
gen8_cs_irq_handler                           97      77     -20
gen8_cs_irq_handler.cold                      33       -     -33
__func__                                   28208   28175     -33

The function name was as large as the function itself?

> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Xiaolin Zhang <xiaolin.zhang at intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c             | 2 +-
>  drivers/gpu/drm/i915/intel_engine_types.h   | 7 +++++++
>  drivers/gpu/drm/i915/intel_guc_submission.c | 2 ++
>  3 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 455b2bf691b5..aa107a78cb36 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1470,7 +1470,7 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
>  
>         if (iir & GT_RENDER_USER_INTERRUPT) {
>                 intel_engine_breadcrumbs_irq(engine);
> -               tasklet |= USES_GUC_SUBMISSION(engine->i915);
> +               tasklet |= intel_engine_needs_breadcrumb_tasklet(engine);
>         }
>  
>         if (tasklet)
> diff --git a/drivers/gpu/drm/i915/intel_engine_types.h b/drivers/gpu/drm/i915/intel_engine_types.h
> index b3249bf6a65f..5c3f567a7a20 100644
> --- a/drivers/gpu/drm/i915/intel_engine_types.h
> +++ b/drivers/gpu/drm/i915/intel_engine_types.h
> @@ -425,6 +425,7 @@ struct intel_engine_cs {
>  #define I915_ENGINE_SUPPORTS_STATS   BIT(1)
>  #define I915_ENGINE_HAS_PREEMPTION   BIT(2)
>  #define I915_ENGINE_HAS_SEMAPHORES   BIT(3)
> +#define I915_ENGINE_NEEDS_BREADCRUMB_TASKLET BIT(4)
>         unsigned int flags;
>  
>         /*
> @@ -508,6 +509,12 @@ intel_engine_has_semaphores(const struct intel_engine_cs *engine)
>         return engine->flags & I915_ENGINE_HAS_SEMAPHORES;
>  }
>  
> +static inline bool
> +intel_engine_needs_breadcrumb_tasklet(const struct intel_engine_cs *engine)
> +{
> +       return engine->flags & I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;
> +}
> +
>  #define instdone_slice_mask(dev_priv__) \
>         (IS_GEN(dev_priv__, 7) ? \
>          1 : RUNTIME_INFO(dev_priv__)->sseu.slice_mask)
> diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
> index c4ad73980988..c58922226d47 100644
> --- a/drivers/gpu/drm/i915/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/intel_guc_submission.c
> @@ -1262,10 +1262,12 @@ static void guc_interrupts_release(struct drm_i915_private *dev_priv)
>  static void guc_submission_park(struct intel_engine_cs *engine)
>  {
>         intel_engine_unpin_breadcrumbs_irq(engine);
> +       engine->flags &= ~I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;
>  }
>  
>  static void guc_submission_unpark(struct intel_engine_cs *engine)
>  {
> +       engine->flags |= I915_ENGINE_NEEDS_BREADCRUMB_TASKLET;
>         intel_engine_pin_breadcrumbs_irq(engine);
>  }
>  
> -- 
> 2.20.1
>