[Intel-xe] [PATCH 04/19] drm/xe: Add helper to get dss per group

[Matt Roper]

On Tue, Mar 07, 2023 at 01:24:31AM -0800, Lucas De Marchi wrote:
> This is already used in intel_gt_mcr and will be used in workarounds.
> Add helpers so the platform-dependency is in a single place.
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_mcr.c      | 2 +-
>  drivers/gpu/drm/xe/xe_gt_topology.c | 6 ++++++
>  drivers/gpu/drm/xe/xe_gt_topology.h | 3 +++
>  3 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.c b/drivers/gpu/drm/xe/xe_gt_mcr.c
> index a42061c4b9d2..694a79b40ec0 100644
> --- a/drivers/gpu/drm/xe/xe_gt_mcr.c
> +++ b/drivers/gpu/drm/xe/xe_gt_mcr.c
> @@ -223,7 +223,7 @@ static void init_steering_dss(struct xe_gt *gt)
>  {
>  	unsigned int dss = min(xe_dss_mask_group_ffs(gt->fuse_topo.g_dss_mask, 0, 0),
>  			       xe_dss_mask_group_ffs(gt->fuse_topo.c_dss_mask, 0, 0));
> -	unsigned int dss_per_grp = gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
> +	unsigned int dss_per_grp = xe_gt_topology_get_dss_per_group(gt);
>  
>  	gt->steering[DSS].group_target = dss / dss_per_grp;
>  	gt->steering[DSS].instance_target = dss % dss_per_grp;
> diff --git a/drivers/gpu/drm/xe/xe_gt_topology.c b/drivers/gpu/drm/xe/xe_gt_topology.c
> index 967f2349c67a..9fe06a46a400 100644
> --- a/drivers/gpu/drm/xe/xe_gt_topology.c
> +++ b/drivers/gpu/drm/xe/xe_gt_topology.c
> @@ -103,6 +103,12 @@ xe_gt_topology_dump(struct xe_gt *gt, struct drm_printer *p)
>  
>  }
>  
> +unsigned int
> +xe_gt_topology_get_dss_per_group(struct xe_gt *gt)

When this shows up as a general interface, it leaves me wondering what a
"group" is.  The rules for DSS steering happen to use gslices on Xe_HP
platforms and cslices on Xe_HPC platforms, but that's just the
platform-specific rules of steering and doesn't automatically translate
into which type of slice would be appropriate to use as a grouping
elsewhere in the driver.

I don't see this new function being used yet in the other patches of
this series, so I'm not sure exactly which workaround(s) plan to re-use
it.  But likely we at least need some kind of clarifying rename for this
function, otherwise it's probably going to get re-used incorrectly
elsewhere in the driver.


Matt

> +{
> +	return gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;
> +}
> +
>  /*
>   * Used to obtain the index of the first DSS.  Can start searching from the
>   * beginning of a specific dss group (e.g., gslice, cslice, etc.) if
> diff --git a/drivers/gpu/drm/xe/xe_gt_topology.h b/drivers/gpu/drm/xe/xe_gt_topology.h
> index 2375f005e0c8..cf8f75a4c7dd 100644
> --- a/drivers/gpu/drm/xe/xe_gt_topology.h
> +++ b/drivers/gpu/drm/xe/xe_gt_topology.h
> @@ -14,6 +14,9 @@ void xe_gt_topology_init(struct xe_gt *gt);
>  
>  void xe_gt_topology_dump(struct xe_gt *gt, struct drm_printer *p);
>  
> +unsigned int
> +xe_gt_topology_get_dss_per_group(struct xe_gt *gt);
> +
>  unsigned int
>  xe_dss_mask_group_ffs(const xe_dss_mask_t mask, int groupsize, int groupnum);
>  
> -- 
> 2.39.0
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation