Re: [PATCH v2 1/6] drm/i915: Add the FIRST_CCS() helper

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 27 Mar 2025, Andi Shyti <andi.shyti@linux.intel.com> wrote:
> From: Andi Shyti <andi.shyti@intel.com>
>
> Some GPUs, like DG2, can host more than one CCS engine. Some
> workarounds or enablements need to happen only once for all the
> engines in the GT—for example, on the engine with the lowest
> instance.
>
> The FIRST_CCS() helper first checks if the engine is a Compute
> engine, and then whether it's the one with the lowest instance.
>
> Signed-off-by: Andi Shyti <andi.shyti@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 54538b6f85df..5cb501393c4b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -619,6 +619,9 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
>  #define CCS_MASK(gt) \
>  	ENGINE_INSTANCES_MASK(gt, CCS0, I915_MAX_CCS)
>  
> +#define FIRST_CCS(e__) \
> +	(CCS_MASK(e__->gt) && (__ffs(CCS_MASK(e__->gt)) == e__->instance))
> +

Could I persuade you to find a more specific header file for this, along
with the CCS_MASK etc.?

BR,
Jani.


>  #define HAS_MEDIA_RATIO_MODE(i915) (INTEL_INFO(i915)->has_media_ratio_mode)
>  
>  /*

-- 
Jani Nikula, Intel