drm/i915: Add function to determine if a slice has a subslice

Add a new function to determine whether a particular slice
has a given subslice.
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/20190823160307.180813-9-stuart.summers@intel.com

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

@@ -10,6 +10,8 @@
 #include <linux/types.h>
 #include <linux/kernel.h>
 
+#include "i915_gem.h"
+
 struct drm_i915_private;
 
 #define GEN_MAX_SLICES		(6) /* CNL upper bound */
@@ -69,6 +71,20 @@ intel_sseu_from_device_info(const struct sseu_dev_info *sseu)
 	return value;
 }
 
+static inline bool
+intel_sseu_has_subslice(const struct sseu_dev_info *sseu, int slice,
+			int subslice)
+{
+	u8 mask;
+	int ss_idx = subslice / BITS_PER_BYTE;
+
+	GEM_BUG_ON(ss_idx >= sseu->ss_stride);
+
+	mask = sseu->subslice_mask[slice * sseu->ss_stride + ss_idx];
+
+	return mask & BIT(subslice % BITS_PER_BYTE);
+}
+
 void intel_sseu_set_info(struct sseu_dev_info *sseu, u8 max_slices,
 			 u8 max_subslices, u8 max_eus_per_subslice);
 

drivers/gpu/drm/i915/intel_device_info.c

@@ -210,12 +210,11 @@ static void gen11_sseu_info_init(struct drm_i915_private *dev_priv)
 			intel_sseu_set_subslices(sseu, s, (ss_en >> ss_idx) &
 							  ss_en_mask);
 
-			for (ss = 0; ss < sseu->max_subslices; ss++) {
-				if (sseu->subslice_mask[s] & BIT(ss))
+			for (ss = 0; ss < sseu->max_subslices; ss++)
+				if (intel_sseu_has_subslice(sseu, s, ss))
 					sseu_set_eus(sseu, s, ss, eu_en);
 		}
 	}
-	}
 	sseu->eu_per_subslice = hweight8(eu_en);
 	sseu->eu_total = compute_eu_total(sseu);
 
@@ -395,7 +394,7 @@ static void gen9_sseu_info_init(struct drm_i915_private *dev_priv)
 			int eu_per_ss;
 			u8 eu_disabled_mask;
 
-			if (!(sseu->subslice_mask[s] & BIT(ss)))
+			if (!intel_sseu_has_subslice(sseu, s, ss))
 				/* skip disabled subslice */
 				continue;
 
@@ -501,7 +500,7 @@ static void broadwell_sseu_info_init(struct drm_i915_private *dev_priv)
 			u8 eu_disabled_mask;
 			u32 n_disabled;
 
-			if (!(sseu->subslice_mask[s] & BIT(ss)))
+			if (!intel_sseu_has_subslice(sseu, s, ss))
 				/* skip disabled subslice */
 				continue;