[PATCH 2/2] drm/i915: Add logical mapping for video decode engines

[Souza, Jose]

On Wed, 2022-03-16 at 16:45 -0700, Lucas De Marchi wrote:
> From: Matthew Brost <matthew.brost at intel.com>
> 
> Add logical mapping for VDBOXs. This mapping is required for
> split-frame workloads, which otherwise fail with
> 
> 	00000000-F8C53528: [GUC] 0441-INVALID_ENGINE_SUBMIT_MASK
> 
> ... if the application is using the logical id to reorder the engines and
> then using it for the batch buffer submission. It's not a big problem on
> media version 11 and 12 as they have only 2 instances of VCS and the
> logical to physical mapping is monotonically increasing - if the
> application is not using the logical id.
> 
> Changing it for the previous platforms allows the media driver
> implementation for the next ones (12.50 and above) to be the same,
> checking the logical id. It should also not introduce any bug for the
> old versions of userspace not checking the id.
> 
> The mapping added here is the complete map needed by XEHPSDV. Previous
> platforms with only 2 instances will just use a partial map and should
> still work.
> 
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> [ Extend the mapping to media versions 11 and 12 and give proper
>   justification in the commit message why ]
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_engine_cs.c | 22 +++++++++++++++++-----
>  1 file changed, 17 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index 8080479f27aa..afa2e61cf729 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -731,12 +731,24 @@ static void populate_logical_ids(struct intel_gt *gt, u8 *logical_ids,
>  
>  static void setup_logical_ids(struct intel_gt *gt, u8 *logical_ids, u8 class)
>  {
> -	int i;
> -	u8 map[MAX_ENGINE_INSTANCE + 1];
> +	/*
> +	 * Logical to physical mapping is needed for proper support
> +	 * to split-frame feature.
> +	 */
> +	if (MEDIA_VER(gt->i915) >= 11 && class == VIDEO_DECODE_CLASS) {
> +		static const u8 map[] = { 0, 2, 4, 6, 1, 3, 5, 7 };

You can drop the static.

Other than that LGTM.
Reviewed-by: José Roberto de Souza <jose.souza at intel.com>

>  
> -	for (i = 0; i < MAX_ENGINE_INSTANCE + 1; ++i)
> -		map[i] = i;
> -	populate_logical_ids(gt, logical_ids, class, map, ARRAY_SIZE(map));
> +		populate_logical_ids(gt, logical_ids, class,
> +				     map, ARRAY_SIZE(map));
> +	} else {
> +		int i;
> +		u8 map[MAX_ENGINE_INSTANCE + 1];
> +
> +		for (i = 0; i < MAX_ENGINE_INSTANCE + 1; ++i)
> +			map[i] = i;
> +		populate_logical_ids(gt, logical_ids, class,
> +				     map, ARRAY_SIZE(map));
> +	}
>  }
>  
>  /**