Re: [Intel-gfx] [PATCH v2 14/14] drm/i915/mtl: Add multicast steering for media GT

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

Hi Matt,

On 01/10/2022 01:45, Matt Roper wrote:
> MTL's media GT only has a single type of steering ("OAADDRM") which
> selects between media slice 0 and media slice 1.  We'll always steer to
> media slice 0 unless it is fused off (which is the case when VD0, VE0,
> and SFC0 are all reported as unavailable).
> 
> Bspec: 67789
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_gt_mcr.c      | 19 +++++++++++++++++--
>   drivers/gpu/drm/i915/gt/intel_gt_types.h    |  1 +
>   drivers/gpu/drm/i915/gt/intel_workarounds.c | 18 +++++++++++++++++-
>   3 files changed, 35 insertions(+), 3 deletions(-)

[snip]

> +static void
> +mtl_media_gt_workarounds_init(struct intel_gt *gt, struct i915_wa_list *wal)
> +{
> +	/*
> +	 * Unlike older platforms, we no longer setup implicit steering here;
> +	 * all MCR accesses are explicitly steered.
> +	 */
> +	if (drm_debug_enabled(DRM_UT_DRIVER)) {
> +		struct drm_printer p = drm_debug_printer("MCR Steering:");
> +
> +		intel_gt_mcr_report_steering(&p, gt, false);
> +	}
> +}
> +
>   static void
>   gt_init_workarounds(struct intel_gt *gt, struct i915_wa_list *wal)
>   {
>   	struct drm_i915_private *i915 = gt->i915;
>   
> -	if (IS_METEORLAKE(i915) && gt->type == GT_PRIMARY)
> +	if (IS_METEORLAKE(i915) && gt->type == GT_MEDIA)
> +		mtl_media_gt_workarounds_init(gt, wal);
> +	else if (IS_METEORLAKE(i915) && gt->type == GT_PRIMARY)
>   		mtl_3d_gt_workarounds_init(gt, wal);
>   	else if (IS_PONTEVECCHIO(i915))
>   		pvc_gt_workarounds_init(gt, wal);

Casually reading only - wouldn't it be nicer if the if-ladder in here 
(gt_init_workarounds) would have a single case per platform, and then 
you'd fork further (3d vs media) in MTL specific function?

Also, series ends up with mtl_media_gt_workarounds_init and 
mtl_3d_gt_workarounds_init apparently 100% identical. You will need two 
copies in the future?

Regards,

Tvrtko