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

[Lucas De Marchi]

On Wed, Mar 08, 2023 at 01:53:38PM -0800, Matt Roper wrote:
>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.

humn... maybe I myself didn't understand the group meaning here.
is group a generic term for cslice/gslice?

>
>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 was supposed to be
"[PATCH 07/19] drm/xe/rtp: Add match helper for gslice fused off", but
then I forgot to replace the hardcoded
`gt_to_xe(gt)->info.platform == XE_PVC ? 8 : 4;` by a call to this
function.


Lucas De Marchi

>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