[PATCH 02/17] drm/i915: introduce gtt page size

[Matthew Auld]

In preparation for supporting huge gtt pages for the ppgtt, we introduce
a gtt_page_size member for gem objects.  We fill in the gtt page size by
scanning the sg table to determine the max page size which satisfies the
alignment for each sg entry.

Signed-off-by: Matthew Auld <matthew.auld at intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Daniel Vetter <daniel at ffwll.ch>
---
 drivers/gpu/drm/i915/i915_drv.h        |  2 ++
 drivers/gpu/drm/i915/i915_gem.c        | 23 +++++++++++++++++++++++
 drivers/gpu/drm/i915/i915_gem_object.h |  2 ++
 3 files changed, 27 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index e18f11f77f35..a7a108d18a2d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2843,6 +2843,8 @@ intel_info(const struct drm_i915_private *dev_priv)
 #define USES_PPGTT(dev_priv)		(i915.enable_ppgtt)
 #define USES_FULL_PPGTT(dev_priv)	(i915.enable_ppgtt >= 2)
 #define USES_FULL_48BIT_PPGTT(dev_priv)	(i915.enable_ppgtt == 3)
+#define HAS_PAGE_SIZE(dev_priv, page_size) \
+	((dev_priv)->info.page_size_mask & (page_size))
 
 #define HAS_OVERLAY(dev_priv)		 ((dev_priv)->info.has_overlay)
 #define OVERLAY_NEEDS_PHYSICAL(dev_priv) \
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0c1cbe98c994..6a5e864d7710 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2294,6 +2294,8 @@ void __i915_gem_object_put_pages(struct drm_i915_gem_object *obj,
 	if (!IS_ERR(pages))
 		obj->ops->put_pages(obj, pages);
 
+	obj->gtt_page_size = 0;
+
 unlock:
 	mutex_unlock(&obj->mm.lock);
 }
@@ -2473,6 +2475,13 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
 				 struct sg_table *pages)
 {
+	struct drm_i915_private *i915 = to_i915(obj->base.dev);
+	unsigned long supported_page_sizes = INTEL_INFO(i915)->page_size_mask;
+	struct scatterlist *sg;
+	unsigned int sg_mask = 0;
+	unsigned int i;
+	unsigned int bit;
+
 	lockdep_assert_held(&obj->mm.lock);
 
 	obj->mm.get_page.sg_pos = pages->sgl;
@@ -2486,6 +2495,20 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
 		__i915_gem_object_pin_pages(obj);
 		obj->mm.quirked = true;
 	}
+
+	for_each_sg(pages->sgl, sg, pages->nents, i)
+		sg_mask |= sg->length;
+
+	GEM_BUG_ON(!sg_mask);
+
+	for_each_set_bit(bit, &supported_page_sizes, BITS_PER_LONG) {
+		if (!IS_ALIGNED(sg_mask, 1 << bit))
+			break;
+
+		obj->gtt_page_size = 1 << bit;
+	}
+
+	GEM_BUG_ON(!HAS_PAGE_SIZE(i915, obj->gtt_page_size));
 }
 
 static int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/i915_gem_object.h b/drivers/gpu/drm/i915/i915_gem_object.h
index 174cf923c236..75beb6a79635 100644
--- a/drivers/gpu/drm/i915/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/i915_gem_object.h
@@ -107,6 +107,8 @@ struct drm_i915_gem_object {
 	unsigned int cache_level:3;
 	unsigned int cache_dirty:1;
 
+	unsigned int gtt_page_size;
+
 	atomic_t frontbuffer_bits;
 	unsigned int frontbuffer_ggtt_origin; /* write once */
 	struct i915_gem_active frontbuffer_write;
-- 
2.9.4