drm/i915: Add subslice stride runtime parameter

Add a new parameter, ss_stride, to the runtime info
structure. This is used to mirror the userspace concept
of subslice stride, which is a range of subslices per slice.

This patch simply adds the definition and updates usage
in the QUERY_TOPOLOGY_INFO handler.

v2: Add GEM_BUG_ON to make sure ss_stride is valid
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/20190823160307.180813-4-stuart.summers@intel.com

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

@@ -14,6 +14,9 @@ void intel_sseu_set_info(struct sseu_dev_info *sseu, u8 max_slices,
 	sseu->max_slices = max_slices;
 	sseu->max_subslices = max_subslices;
 	sseu->max_eus_per_subslice = max_eus_per_subslice;
+
+	sseu->ss_stride = GEN_SSEU_STRIDE(sseu->max_subslices);
+	GEM_BUG_ON(sseu->ss_stride > GEN_MAX_SUBSLICE_STRIDE);
 }
 
 unsigned int

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

@@ -15,6 +15,7 @@ struct drm_i915_private;
 #define GEN_MAX_SLICES		(6) /* CNL upper bound */
 #define GEN_MAX_SUBSLICES	(8) /* ICL upper bound */
 #define GEN_SSEU_STRIDE(max_entries) DIV_ROUND_UP(max_entries, BITS_PER_BYTE)
+#define GEN_MAX_SUBSLICE_STRIDE GEN_SSEU_STRIDE(GEN_MAX_SUBSLICES)
 
 struct sseu_dev_info {
 	u8 slice_mask;
@@ -33,6 +34,8 @@ struct sseu_dev_info {
 	u8 max_subslices;
 	u8 max_eus_per_subslice;
 
+	u8 ss_stride;
+
 	/* We don't have more than 8 eus per subslice at the moment and as we
 	 * store eus enabled using bits, no need to multiply by eus per
 	 * subslice.

drivers/gpu/drm/i915/i915_query.c

@@ -37,7 +37,6 @@ static int query_topology_info(struct drm_i915_private *dev_priv,
 	const struct sseu_dev_info *sseu = &RUNTIME_INFO(dev_priv)->sseu;
 	struct drm_i915_query_topology_info topo;
 	u32 slice_length, subslice_length, eu_length, total_length;
-	u8 subslice_stride = GEN_SSEU_STRIDE(sseu->max_subslices);
 	u8 eu_stride = GEN_SSEU_STRIDE(sseu->max_eus_per_subslice);
 	int ret;
 
@@ -50,7 +49,7 @@ static int query_topology_info(struct drm_i915_private *dev_priv,
 	BUILD_BUG_ON(sizeof(u8) != sizeof(sseu->slice_mask));
 
 	slice_length = sizeof(sseu->slice_mask);
-	subslice_length = sseu->max_slices * subslice_stride;
+	subslice_length = sseu->max_slices * sseu->ss_stride;
 	eu_length = sseu->max_slices * sseu->max_subslices * eu_stride;
 	total_length = sizeof(topo) + slice_length + subslice_length +
 		       eu_length;
@@ -69,7 +68,7 @@ static int query_topology_info(struct drm_i915_private *dev_priv,
 	topo.max_eus_per_subslice = sseu->max_eus_per_subslice;
 
 	topo.subslice_offset = slice_length;
-	topo.subslice_stride = subslice_stride;
+	topo.subslice_stride = sseu->ss_stride;
 	topo.eu_offset = slice_length + subslice_length;
 	topo.eu_stride = eu_stride;