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

[Lucas De Marchi]

On Wed, Mar 08, 2023 at 02:16:48PM -0800, Lucas De Marchi wrote:
>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?

btw the term "group" is already used in e.g. xe_dss_mask_group_ffs()
exported in drivers/gpu/drm/xe/xe_gt_topology.h

Lucas De Marchi

>
>>
>>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