[igt-dev] [PATCH i-g-t v5 01/12] include/drm-uapi: memory region gtt_alignment support

[Niranjana Vishwanathapura]

Pull in gtt_alignment addition in drm_i915_memory_region_info
uapi and update library to include this field.

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at intel.com>
---
 include/drm-uapi/i915_drm.h    | 30 ++++++++++++++++++++++++++++--
 lib/i915/intel_memory_region.c |  1 +
 lib/i915/intel_memory_region.h |  1 +
 3 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/include/drm-uapi/i915_drm.h b/include/drm-uapi/i915_drm.h
index ae9558b3d9..b3a200fc5d 100644
--- a/include/drm-uapi/i915_drm.h
+++ b/include/drm-uapi/i915_drm.h
@@ -3215,8 +3215,34 @@ struct drm_i915_memory_region_info {
 	/** @region: The class:instance pair encoding */
 	struct drm_i915_gem_memory_class_instance region;
 
-	/** @rsvd0: MBZ */
-	__u32 rsvd0;
+	union {
+		/** @rsvd0: MBZ */
+		__u32 rsvd0;
+
+		/**
+		 * @gtt_alignment:
+		 *
+		 * The minimum required GTT alignment for this type of memory.
+		 * When allocating a GTT address it must be aligned to this
+		 * value or larger. On some platforms the kernel might opt to
+		 * using 64K pages for I915_MEMORY_CLASS_DEVICE, where 64K GTT
+		 * pages can then be used if we also use 64K GTT alignment.
+		 *
+		 * NOTE: If this is zero then this must be an older
+		 * kernel which lacks support for this field.
+		 *
+		 * Side note: For larger objects (especially for
+		 * I915_MEMORY_CLASS_DEVICE), like 2M+ in size, userspace should
+		 * consider potentially bumping the GTT alignment to say 2M,
+		 * which could potentially increase the likelihood of the kernel
+		 * being able to utilise 2M GTT pages underneath, if the layout
+		 * of the physical pages allows it.  On some configurations we
+		 * can then also use a more efficient page-table layout, if we
+		 * can't use the more desirable 2M GTT page, so long as we know
+		 * that the entire page-table will be used by this object.
+		 */
+		__u32 gtt_alignment;
+	};
 
 	/**
 	 * @probed_size: Memory probed by the driver
diff --git a/lib/i915/intel_memory_region.c b/lib/i915/intel_memory_region.c
index 84e1bceb38..cbe27d6714 100644
--- a/lib/i915/intel_memory_region.c
+++ b/lib/i915/intel_memory_region.c
@@ -944,6 +944,7 @@ struct gem_memory_region *__gem_get_memory_regions(int i915)
 
 		r->ci = info->regions[i].region;
 		r->size = info->regions[i].probed_size;
+		r->gtt_alignment = info->regions[i].gtt_alignment;
 		r->cpu_size = info->regions[i].probed_cpu_visible_size;
 		if (r->size == -1ull)
 			r->size = igt_get_avail_ram_mb() << 20;
diff --git a/lib/i915/intel_memory_region.h b/lib/i915/intel_memory_region.h
index 425bda0ec7..84abb95b1a 100644
--- a/lib/i915/intel_memory_region.h
+++ b/lib/i915/intel_memory_region.h
@@ -174,6 +174,7 @@ struct gem_memory_region {
 	char *name;
 
 	struct drm_i915_gem_memory_class_instance ci;
+	uint64_t gtt_alignment;
 	uint64_t size;
 	uint64_t cpu_size;
 };
-- 
2.21.0.rc0.32.g243a4c7e27