[PATCH] drm/xe: Upgrade complaint about missing slice info

[Summers, Stuart]

On Fri, 2025-01-17 at 16:54 -0800, John.C.Harrison at Intel.com wrote:
> From: John Harrison <John.C.Harrison at Intel.com>
> 
> The steering code needs to know slice/subslice counts and this
> information should be retrieved from the hwconfig table. However,
> earlier platforms don't have it, hence the KMD has a fallback path.
> Newer platforms really should have the entries and if they are
> missing
> that is a bug that needs to be fixed in the table.
> 
> So update the complaint to be an error on newer platforms and remove
> it completely for older ones that we know are bad (but are not POR
> for
> the Xe driver anyway). Also, re-word the message a little to make it
> clearer what the issue is.
> 
> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_mcr.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.c
> b/drivers/gpu/drm/xe/xe_gt_mcr.c
> index a1676b787fdc..605aad3554e7 100644
> --- a/drivers/gpu/drm/xe/xe_gt_mcr.c
> +++ b/drivers/gpu/drm/xe/xe_gt_mcr.c
> @@ -341,7 +341,13 @@ static unsigned int dss_per_group(struct xe_gt
> *gt)
>         return DIV_ROUND_UP(max_subslices, max_slices);
>  
>  fallback:
> -       xe_gt_dbg(gt, "GuC hwconfig cannot provide dss/slice; using
> typical fallback values\n");

Agree with Rodrigo that this is still interesting for older platforms
to show the expectation.

> +       /*
> +        * Some older platforms don't have tables or don't have
> complete tables.
> +        * Newer platforms should always have the required info.
> +        */
> +       if (GRAPHICS_VERx100(gt_to_xe(gt)) >= 2000)
> +               xe_gt_err(gt, "Slice/Subslice counts missing from
> hwconfig table; using typical fallback values\n");

I understand the intent here, but IMO it would be better for this to be
a warning.

Thanks,
Stuart

> +
>         if (gt_to_xe(gt)->info.platform == XE_PVC)
>                 return 8;
>         else if (GRAPHICS_VERx100(gt_to_xe(gt)) >= 1250)