drm/i915: Add a new "remapped" gtt_view

To overcome display engine stride limits we'll want to remap the
pages in the GTT. To that end we need a new gtt_view type which
is just like the "rotated" type except not rotated.

v2: Use intel_remapped_plane_info base type
    s/unused/unused_mbz/ (Chris)
    Separate BUILD_BUG_ON()s (Chris)
    Use I915_GTT_PAGE_SIZE (Chris)
v3: Use i915_gem_object_get_dma_address() (Chris)
    Trim the sg (Tvrtko)
v4: Actually trim this time. Limit the max length
    to one row of pages to keep things simple

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190509122159.24376-2-ville.syrjala@linux.intel.com
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -212,6 +212,18 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
 					   vma->ggtt_view.rotated.plane[1].offset);
 				break;
 
+			case I915_GGTT_VIEW_REMAPPED:
+				seq_printf(m, ", remapped [(%ux%u, stride=%u, offset=%u), (%ux%u, stride=%u, offset=%u)]",
+					   vma->ggtt_view.remapped.plane[0].width,
+					   vma->ggtt_view.remapped.plane[0].height,
+					   vma->ggtt_view.remapped.plane[0].stride,
+					   vma->ggtt_view.remapped.plane[0].offset,
+					   vma->ggtt_view.remapped.plane[1].width,
+					   vma->ggtt_view.remapped.plane[1].height,
+					   vma->ggtt_view.remapped.plane[1].stride,
+					   vma->ggtt_view.remapped.plane[1].offset);
+				break;
+
 			default:
 				MISSING_CASE(vma->ggtt_view.type);
 				break;

drivers/gpu/drm/i915/i915_drv.h

@@ -2864,6 +2864,10 @@ i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj,
 			       unsigned int n);
 
 dma_addr_t
+i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
+				    unsigned long n,
+				    unsigned int *len);
+dma_addr_t
 i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
 				unsigned long n);
 

drivers/gpu/drm/i915/i915_gem.c

@@ -5081,16 +5081,29 @@ i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj,
 }
 
 dma_addr_t
-i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
-				unsigned long n)
+i915_gem_object_get_dma_address_len(struct drm_i915_gem_object *obj,
+				    unsigned long n,
+				    unsigned int *len)
 {
 	struct scatterlist *sg;
 	unsigned int offset;
 
 	sg = i915_gem_object_get_sg(obj, n, &offset);
+
+	if (len)
+		*len = sg_dma_len(sg) - (offset << PAGE_SHIFT);
+
 	return sg_dma_address(sg) + (offset << PAGE_SHIFT);
 }
 
+dma_addr_t
+i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
+				unsigned long n)
+{
+	return i915_gem_object_get_dma_address_len(obj, n, NULL);
+}
+
+
 int i915_gem_object_attach_phys(struct drm_i915_gem_object *obj, int align)
 {
 	struct sg_table *pages;

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -3608,6 +3608,89 @@ err_st_alloc:
 	return ERR_PTR(ret);
 }
 
+static struct scatterlist *
+remap_pages(struct drm_i915_gem_object *obj, unsigned int offset,
+	    unsigned int width, unsigned int height,
+	    unsigned int stride,
+	    struct sg_table *st, struct scatterlist *sg)
+{
+	unsigned int row;
+
+	for (row = 0; row < height; row++) {
+		unsigned int left = width * I915_GTT_PAGE_SIZE;
+
+		while (left) {
+			dma_addr_t addr;
+			unsigned int length;
+
+			/* We don't need the pages, but need to initialize
+			 * the entries so the sg list can be happily traversed.
+			 * The only thing we need are DMA addresses.
+			 */
+
+			addr = i915_gem_object_get_dma_address_len(obj, offset, &length);
+
+			length = min(left, length);
+
+			st->nents++;
+
+			sg_set_page(sg, NULL, length, 0);
+			sg_dma_address(sg) = addr;
+			sg_dma_len(sg) = length;
+			sg = sg_next(sg);
+
+			offset += length / I915_GTT_PAGE_SIZE;
+			left -= length;
+		}
+
+		offset += stride - width;
+	}
+
+	return sg;
+}
+
+static noinline struct sg_table *
+intel_remap_pages(struct intel_remapped_info *rem_info,
+		  struct drm_i915_gem_object *obj)
+{
+	unsigned int size = intel_remapped_info_size(rem_info);
+	struct sg_table *st;
+	struct scatterlist *sg;
+	int ret = -ENOMEM;
+	int i;
+
+	/* Allocate target SG list. */
+	st = kmalloc(sizeof(*st), GFP_KERNEL);
+	if (!st)
+		goto err_st_alloc;
+
+	ret = sg_alloc_table(st, size, GFP_KERNEL);
+	if (ret)
+		goto err_sg_alloc;
+
+	st->nents = 0;
+	sg = st->sgl;
+
+	for (i = 0 ; i < ARRAY_SIZE(rem_info->plane); i++) {
+		sg = remap_pages(obj, rem_info->plane[i].offset,
+				 rem_info->plane[i].width, rem_info->plane[i].height,
+				 rem_info->plane[i].stride, st, sg);
+	}
+
+	i915_sg_trim(st);
+
+	return st;
+
+err_sg_alloc:
+	kfree(st);
+err_st_alloc:
+
+	DRM_DEBUG_DRIVER("Failed to create remapped mapping for object size %zu! (%ux%u tiles, %u pages)\n",
+			 obj->base.size, rem_info->plane[0].width, rem_info->plane[0].height, size);
+
+	return ERR_PTR(ret);
+}
+
 static noinline struct sg_table *
 intel_partial_pages(const struct i915_ggtt_view *view,
 		    struct drm_i915_gem_object *obj)
@@ -3686,6 +3769,11 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma)
 			intel_rotate_pages(&vma->ggtt_view.rotated, vma->obj);
 		break;
 
+	case I915_GGTT_VIEW_REMAPPED:
+		vma->pages =
+			intel_remap_pages(&vma->ggtt_view.remapped, vma->obj);
+		break;
+
 	case I915_GGTT_VIEW_PARTIAL:
 		vma->pages = intel_partial_pages(&vma->ggtt_view, vma->obj);
 		break;

drivers/gpu/drm/i915/i915_gem_gtt.h

@@ -163,11 +163,18 @@ typedef u64 gen8_ppgtt_pml4e_t;
 
 struct sg_table;
 
+struct intel_remapped_plane_info {
+	/* in gtt pages */
+	unsigned int width, height, stride, offset;
+} __packed;
+
+struct intel_remapped_info {
+	struct intel_remapped_plane_info plane[2];
+	unsigned int unused_mbz;
+} __packed;
+
 struct intel_rotation_info {
-	struct intel_rotation_plane_info {
-		/* tiles */
-		unsigned int width, height, stride, offset;
-	} plane[2];
+	struct intel_remapped_plane_info plane[2];
 } __packed;
 
 struct intel_partial_info {
@@ -179,12 +186,20 @@ enum i915_ggtt_view_type {
 	I915_GGTT_VIEW_NORMAL = 0,
 	I915_GGTT_VIEW_ROTATED = sizeof(struct intel_rotation_info),
 	I915_GGTT_VIEW_PARTIAL = sizeof(struct intel_partial_info),
+	I915_GGTT_VIEW_REMAPPED = sizeof(struct intel_remapped_info),
 };
 
 static inline void assert_i915_gem_gtt_types(void)
 {
 	BUILD_BUG_ON(sizeof(struct intel_rotation_info) != 8*sizeof(unsigned int));
 	BUILD_BUG_ON(sizeof(struct intel_partial_info) != sizeof(u64) + sizeof(unsigned int));
+	BUILD_BUG_ON(sizeof(struct intel_remapped_info) != 9*sizeof(unsigned int));
+
+	/* Check that rotation/remapped shares offsets for simplicity */
+	BUILD_BUG_ON(offsetof(struct intel_remapped_info, plane[0]) !=
+		     offsetof(struct intel_rotation_info, plane[0]));
+	BUILD_BUG_ON(offsetofend(struct intel_remapped_info, plane[1]) !=
+		     offsetofend(struct intel_rotation_info, plane[1]));
 
 	/* As we encode the size of each branch inside the union into its type,
 	 * we have to be careful that each branch has a unique size.
@@ -193,6 +208,7 @@ static inline void assert_i915_gem_gtt_types(void)
 	case I915_GGTT_VIEW_NORMAL:
 	case I915_GGTT_VIEW_PARTIAL:
 	case I915_GGTT_VIEW_ROTATED:
+	case I915_GGTT_VIEW_REMAPPED:
 		/* gcc complains if these are identical cases */
 		break;
 	}
@@ -204,6 +220,7 @@ struct i915_ggtt_view {
 		/* Members need to contain no holes/padding */
 		struct intel_partial_info partial;
 		struct intel_rotation_info rotated;
+		struct intel_remapped_info remapped;
 	};
 };
 

drivers/gpu/drm/i915/i915_vma.c

@@ -159,6 +159,9 @@ vma_create(struct drm_i915_gem_object *obj,
 		} else if (view->type == I915_GGTT_VIEW_ROTATED) {
 			vma->size = intel_rotation_info_size(&view->rotated);
 			vma->size <<= PAGE_SHIFT;
+		} else if (view->type == I915_GGTT_VIEW_REMAPPED) {
+			vma->size = intel_remapped_info_size(&view->remapped);
+			vma->size <<= PAGE_SHIFT;
 		}
 	}
 
@@ -484,7 +487,8 @@ void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
 	 * Explicitly disable for rotated VMA since the display does not
 	 * need the fence and the VMA is not accessible to other users.
 	 */
-	if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED)
+	if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED ||
+	    vma->ggtt_view.type == I915_GGTT_VIEW_REMAPPED)
 		return;
 
 	fenceable = (vma->node.size >= vma->fence_size &&

drivers/gpu/drm/i915/i915_vma.h

@@ -277,8 +277,11 @@ i915_vma_compare(struct i915_vma *vma,
 	 */
 	BUILD_BUG_ON(I915_GGTT_VIEW_NORMAL >= I915_GGTT_VIEW_PARTIAL);
 	BUILD_BUG_ON(I915_GGTT_VIEW_PARTIAL >= I915_GGTT_VIEW_ROTATED);
+	BUILD_BUG_ON(I915_GGTT_VIEW_ROTATED >= I915_GGTT_VIEW_REMAPPED);
 	BUILD_BUG_ON(offsetof(typeof(*view), rotated) !=
 		     offsetof(typeof(*view), partial));
+	BUILD_BUG_ON(offsetof(typeof(*view), rotated) !=
+		     offsetof(typeof(*view), remapped));
 	return memcmp(&vma->ggtt_view.partial, &view->partial, view->type);
 }
 

drivers/gpu/drm/i915/intel_display.c

@@ -1997,6 +1997,17 @@ unsigned int intel_rotation_info_size(const struct intel_rotation_info *rot_info
 	return size;
 }
 
+unsigned int intel_remapped_info_size(const struct intel_remapped_info *rem_info)
+{
+	unsigned int size = 0;
+	int i;
+
+	for (i = 0 ; i < ARRAY_SIZE(rem_info->plane); i++)
+		size += rem_info->plane[i].width * rem_info->plane[i].height;
+
+	return size;
+}
+
 static void
 intel_fill_fb_ggtt_view(struct i915_ggtt_view *view,
 			const struct drm_framebuffer *fb,

drivers/gpu/drm/i915/intel_drv.h

@@ -1461,6 +1461,7 @@ unsigned int intel_fb_align_height(const struct drm_framebuffer *fb,
 void intel_add_fb_offsets(int *x, int *y,
 			  const struct intel_plane_state *state, int plane);
 unsigned int intel_rotation_info_size(const struct intel_rotation_info *rot_info);
+unsigned int intel_remapped_info_size(const struct intel_remapped_info *rem_info);
 bool intel_has_pending_fb_unpin(struct drm_i915_private *dev_priv);
 void intel_mark_busy(struct drm_i915_private *dev_priv);
 void intel_mark_idle(struct drm_i915_private *dev_priv);

drivers/gpu/drm/i915/selftests/i915_vma.c

@@ -397,8 +397,8 @@ assert_rotated(struct drm_i915_gem_object *obj,
 	return sg;
 }
 
-static unsigned int rotated_size(const struct intel_rotation_plane_info *a,
-				 const struct intel_rotation_plane_info *b)
+static unsigned int rotated_size(const struct intel_remapped_plane_info *a,
+				 const struct intel_remapped_plane_info *b)
 {
 	return a->width * a->height + b->width * b->height;
 }
@@ -408,7 +408,7 @@ static int igt_vma_rotate(void *arg)
 	struct i915_ggtt *ggtt = arg;
 	struct i915_address_space *vm = &ggtt->vm;
 	struct drm_i915_gem_object *obj;
-	const struct intel_rotation_plane_info planes[] = {
+	const struct intel_remapped_plane_info planes[] = {
 		{ .width = 1, .height = 1, .stride = 1 },
 		{ .width = 2, .height = 2, .stride = 2 },
 		{ .width = 4, .height = 4, .stride = 4 },