Re: [PATCH] drm/i915/gt: Refactor uabi engine class/instance list creation

[Nirmoy Das <nirmoy.das@linux.intel.com>]

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Hi Andi,

On 4/17/2024 12:49 AM, Andi Shyti wrote:
> For the upcoming changes we need a cleaner way to build the list
> of uabi engines.
>
> Suggested-by: Tvrtko Ursulin<tvrtko.ursulin@intel.com>
> Signed-off-by: Andi Shyti<andi.shyti@linux.intel.com>
> ---
> Hi,
>
> just sending this patch to unburden the coming series from this
> single patch inherited from a previously sent series.
>
> Andi
>
>   drivers/gpu/drm/i915/gt/intel_engine_user.c | 29 ++++++++++++---------
>   1 file changed, 17 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_user.c b/drivers/gpu/drm/i915/gt/intel_engine_user.c
> index 833987015b8b..11cc06c0c785 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_user.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_user.c
> @@ -203,7 +203,7 @@ static void engine_rename(struct intel_engine_cs *engine, const char *name, u16
>   
>   void intel_engines_driver_register(struct drm_i915_private *i915)
>   {
> -	u16 name_instance, other_instance = 0;
> +	u16 class_instance[I915_LAST_UABI_ENGINE_CLASS + 2] = { };
+2 is confusing here. I think we need a better macro.
>   	struct legacy_ring ring = {};
>   	struct list_head *it, *next;
>   	struct rb_node **p, *prev;
> @@ -214,6 +214,8 @@ void intel_engines_driver_register(struct drm_i915_private *i915)
>   	prev = NULL;
>   	p = &i915->uabi_engines.rb_node;
>   	list_for_each_safe(it, next, &engines) {
> +		u16 uabi_class;
> +
>   		struct intel_engine_cs *engine =
>   			container_of(it, typeof(*engine), uabi_list);
>   
> @@ -222,15 +224,14 @@ void intel_engines_driver_register(struct drm_i915_private *i915)
>   
>   		GEM_BUG_ON(engine->class >= ARRAY_SIZE(uabi_classes));
>   		engine->uabi_class = uabi_classes[engine->class];
> -		if (engine->uabi_class == I915_NO_UABI_CLASS) {
> -			name_instance = other_instance++;
> -		} else {
> -			GEM_BUG_ON(engine->uabi_class >=
> -				   ARRAY_SIZE(i915->engine_uabi_class_count));
> -			name_instance =
> -				i915->engine_uabi_class_count[engine->uabi_class]++;
> -		}
> -		engine->uabi_instance = name_instance;
> +
> +		if (engine->uabi_class == I915_NO_UABI_CLASS)
> +			uabi_class = I915_LAST_UABI_ENGINE_CLASS + 1;
> +		else
> +			uabi_class = engine->uabi_class;
> +
> +		GEM_BUG_ON(uabi_class >= ARRAY_SIZE(class_instance));
> +		engine->uabi_instance = class_instance[uabi_class]++;
>   
>   		/*
>   		 * Replace the internal name with the final user and log facing
> @@ -238,11 +239,15 @@ void intel_engines_driver_register(struct drm_i915_private *i915)
>   		 */
>   		engine_rename(engine,
>   			      intel_engine_class_repr(engine->class),
> -			      name_instance);
> +			      engine->uabi_instance);
>   
> -		if (engine->uabi_class == I915_NO_UABI_CLASS)
> +		if (uabi_class > I915_LAST_UABI_ENGINE_CLASS)
>   			continue;
>   
> +		GEM_BUG_ON(uabi_class >=
> +			   ARRAY_SIZE(i915->engine_uabi_class_count));
> +		i915->engine_uabi_class_count[uabi_class]++;
Shouldn't this be  i915->engine_uabi_class_count[uabi_class] = 
class_instance[uabi_class]; ?

What I see is that this patch mainly adding this class_instance array 
and rest looks the same.
May be it make sense to add other upcoming  patches to better understand 
why we need this patch.

Regards,
Nirmoy

> +
>   		rb_link_node(&engine->uabi_node, prev, p);
>   		rb_insert_color(&engine->uabi_node, &i915->uabi_engines);
>   

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