+struct drm_i915_query_item {
+ __u64 query_id;
+#define DRM_I915_QUERY_TOPOLOGY_INFO 1
+
+ /*
+ * When set to zero by userspace, this is filled with the size of the
+ * data to be written at the data_ptr pointer. The kernel sets this
+ * value to a negative value to signal an error on a particular query
+ * item.
+ */
+ __s32 length;
+
+ /*
+ * Unused for now. Must be cleared to zero.
+ */
+ __u32 flags;
+
+ /*
+ * Data will be written at the location pointed by data_ptr when the
+ * value of length matches the length of the data to be written by the
+ * kernel.
+ */
+ __u64 data_ptr;
+};
+
+struct drm_i915_query {
+ __u32 num_items;
+
+ /*
+ * Unused for now. Must be cleared to zero.
+ */
+ __u32 flags;
+
+ /*
+ * This points to an array of num_items drm_i915_query_item structures.
+ */
+ __u64 items_ptr;
+};
+
+/*
+ * Data written by the kernel with query DRM_I915_QUERY_TOPOLOGY_INFO :
+ *
+ * data: contains the 3 pieces of information :
+ *
+ * - the slice mask with one bit per slice telling whether a slice is
+ * available. The availability of slice X can be queried with the following
+ * formula :
+ *
+ * (data[X / 8] >> (X % 8)) & 1
+ *
+ * - the subslice mask for each slice with one bit per subslice telling
+ * whether a subslice is available. The availability of subslice Y in slice
+ * X can be queried with the following formula :
+ *
+ * (data[subslice_offset +
+ * X * subslice_stride +
+ * Y / 8] >> (Y % 8)) & 1
+ *
+ * - the EU mask for each subslice in each slice with one bit per EU telling
+ * whether an EU is available. The availability of EU Z in subslice Y in
+ * slice X can be queried with the following formula :
+ *
+ * (data[eu_offset +
+ * (X * max_subslices + Y) * eu_stride +
+ * Z / 8] >> (Z % 8)) & 1
+ */
+struct drm_i915_query_topology_info {
+ /*
+ * Unused for now. Must be cleared to zero.
+ */
+ __u16 flags;
+
+ __u16 max_slices;
+ __u16 max_subslices;
+ __u16 max_eus_per_subslice;
+
+ /*
+ * Offset in data[] at which the subslice masks are stored.
+ */
+ __u16 subslice_offset;
+
+ /*
+ * Stride at which each of the subslice masks for each slice are
+ * stored.
+ */
+ __u16 subslice_stride;
+
+ /*
+ * Offset in data[] at which the EU masks are stored.
+ */
+ __u16 eu_offset;
+
+ /*
+ * Stride at which each of the EU masks for each subslice are stored.
+ */
+ __u16 eu_stride;
+
+ __u8 data[];
+};
+