drm/i915: Use subslice stride to set subslices for a given slice

Add a subslice stride calculation when setting subslices. This
aligns more closely with the userspace expectation of the subslice
mask structure.

v2: Use local variable for subslice_mask on HSW and
    clean up a few other subslice_mask local variable
    changes
v3: Add GEM_BUG_ON for ss_stride to prevent array overflow (Chris)
    Split main set function and refactors in intel_device_info.c
    into separate patches (Chris)
v4: Reduce ss_stride size check when setting subslices per slice
    based on actual expected max stride (Chris)
    Move that GEM_BUG_ON check for the ss_stride out to the patch
    which adds the ss_stride
v5: Use memcpy instead of looping through each stride index

Signed-off-by: Stuart Summers <stuart.summers@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190823160307.180813-8-stuart.summers@intel.com

drivers/gpu/drm/i915/gt/intel_sseu.c

@@ -33,9 +33,11 @@ intel_sseu_subslice_total(const struct sseu_dev_info *sseu)
 }
 
 void intel_sseu_set_subslices(struct sseu_dev_info *sseu, int slice,
-			      u8 ss_mask)
+			      u32 ss_mask)
 {
-	sseu->subslice_mask[slice] = ss_mask;
+	int offset = slice * sseu->ss_stride;
+
+	memcpy(&sseu->subslice_mask[offset], &ss_mask, sseu->ss_stride);
 }
 
 unsigned int

drivers/gpu/drm/i915/gt/intel_sseu.h

@@ -79,7 +79,7 @@ unsigned int
 intel_sseu_subslices_per_slice(const struct sseu_dev_info *sseu, u8 slice);
 
 void intel_sseu_set_subslices(struct sseu_dev_info *sseu, int slice,
-			      u8 ss_mask);
+			      u32 ss_mask);
 
 u32 intel_sseu_make_rpcs(struct drm_i915_private *i915,
 			 const struct intel_sseu *req_sseu);