[PATCH 5/7] drm/i915/vlv: Increase the utilization of stolen memory on VLV.

[akash.goel@intel.com]

From: Akash Goel <akash.goel@intel.com>

On VLV, 64MB of system memory was being reserved for stolen
area, but ~8MB of it was being utilized.
Increased the utilization of Stolen area by allocating
User created Frame buffers(only X Tiled) from it.
User Frame buffers are suitable for allocation from stolen area,
as its very unlikely that they are not accessed from CPU side.
And its even more unlikely that the Tiled(X) buffers will be
accessed directly from the CPU side. And any allocation
from stolen area is not directly CPU accessible, but
accessible only through the aperture space.
With 1080p sized frame buffers (32 bpp), the allocation of 6-7
frame buffers itself gives almost the full utilization of
stolen area.

Signed-off-by: Akash Goel <akash.goel@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h        |  1 +
 drivers/gpu/drm/i915/i915_gem.c        | 21 ++++++++
 drivers/gpu/drm/i915/i915_gem_stolen.c | 93 ++++++++++++++++++++++++++++++++++
 3 files changed, 115 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 1bcc543..db29537 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2376,6 +2376,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 					       u32 stolen_offset,
 					       u32 gtt_offset,
 					       u32 size);
+void i915_gem_object_move_to_stolen(struct drm_i915_gem_object *obj);
 void i915_gem_object_release_stolen(struct drm_i915_gem_object *obj);
 
 /* i915_gem_tiling.c */
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 656406d..24f93ef 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3915,6 +3915,27 @@ i915_gem_object_pin(struct drm_i915_gem_object *obj,
 		}
 	}
 
+	/* Try to allocate the physical space for the GEM object,
+	 * representing the User frame buffer, from the stolen area.
+	 * But if there is no sufficient free space left in stolen
+	 * area, will fallback to shmem.
+	 */
+	if (obj->user_fb == 1) {
+		if (obj->pages == NULL) {
+			if (obj->tiling_mode == I915_TILING_X) {
+				/* Tiled(X) Scanout buffers are more suitable
+				 * for allocation from stolen area, as its very
+				 * unlikely that they will be accessed directly
+				 * from the CPU side and any allocation from
+				 * stolen area is not directly CPU accessible,
+				 * but accessible only through the aperture
+				 * space.
+				 */
+				i915_gem_object_move_to_stolen(obj);
+			}
+		}
+	}
+
 	if (!i915_gem_obj_bound(obj, vm)) {
 		ret = i915_gem_object_bind_to_vm(obj, vm, alignment,
 						 map_and_fenceable,
diff --git a/drivers/gpu/drm/i915/i915_gem_stolen.c b/drivers/gpu/drm/i915/i915_gem_stolen.c
index 5cf97d6..29c22f9 100644
--- a/drivers/gpu/drm/i915/i915_gem_stolen.c
+++ b/drivers/gpu/drm/i915/i915_gem_stolen.c
@@ -29,6 +29,7 @@
 #include <drm/drmP.h>
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
+#include <linux/shmem_fs.h>
 
 /*
  * The BIOS typically reserves some of the system's memory for the exclusive
@@ -370,6 +371,98 @@ i915_gem_object_create_stolen(struct drm_device *dev, u32 size)
 	return NULL;
 }
 
+void
+i915_gem_object_move_to_stolen(struct drm_i915_gem_object *obj)
+{
+	struct drm_device *dev = obj->base.dev;
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	struct drm_mm_node *stolen;
+	u32 size = obj->base.size;
+	int ret = 0;
+
+	if (!IS_VALLEYVIEW(dev)) {
+		return;
+	}
+
+	if (obj->stolen) {
+		BUG_ON(obj->pages == NULL);
+		return;
+	}
+
+	if (!drm_mm_initialized(&dev_priv->mm.stolen))
+		return;
+
+	if (size == 0)
+		return;
+
+	/* Check if already shmem space has been allocated for the object
+	 * or not. We cannot rely upon on the value of 'pages' field for this.
+	 * As even though if the 'pages' field is NULL, it does not actually
+	 * indicate that the backing physical space (shmem) is currently not
+	 * reserved for the object, as the object may not get purged/truncated
+	 * on the calll to 'put_pages_gtt'.
+	 */
+	if (obj->base.filp) {
+		struct inode *inode = file_inode(obj->base.filp);
+		struct shmem_inode_info *info = SHMEM_I(inode);
+		if (!inode)
+			return;
+		spin_lock(&info->lock);
+		/* The alloced field stores how many data pages are
+		 * allocated to the file.
+		 */
+		ret = info->alloced;
+		spin_unlock(&info->lock);
+		if (ret > 0) {
+			DRM_DEBUG_DRIVER(
+				"Already shmem space alloced, %d pges\n", ret);
+			return;
+		}
+	}
+
+	stolen = kzalloc(sizeof(*stolen), GFP_KERNEL);
+	if (!stolen)
+		return;
+
+	ret = drm_mm_insert_node(&dev_priv->mm.stolen, stolen, size,
+				 4096, DRM_MM_SEARCH_DEFAULT);
+	if (ret) {
+		kfree(stolen);
+		DRM_DEBUG_DRIVER("ran out of stolen space\n");
+		return;
+	}
+
+	/* Set up the object to use the stolen memory,
+	 * backing store no longer managed by shmem layer */
+	drm_gem_object_release(&(obj->base));
+	obj->base.filp = NULL;
+	obj->ops = &i915_gem_object_stolen_ops;
+
+	obj->pages = i915_pages_create_for_stolen(dev,
+						stolen->start, stolen->size);
+	if (obj->pages == NULL)
+		goto cleanup;
+
+	i915_gem_object_pin_pages(obj);
+	list_add_tail(&obj->global_list, &dev_priv->mm.unbound_list);
+	obj->has_dma_mapping = true;
+	obj->stolen = stolen;
+
+	DRM_DEBUG_DRIVER("Obj moved to stolen, ptr = %p, size = %x\n",
+			 obj, size);
+
+	obj->base.read_domains = I915_GEM_DOMAIN_CPU | I915_GEM_DOMAIN_GTT;
+	obj->cache_level = HAS_LLC(dev) ? I915_CACHE_LLC : I915_CACHE_NONE;
+
+	/* No zeroing-out of buffers allocated from stolen area */
+	return;
+
+cleanup:
+	drm_mm_remove_node(stolen);
+	kfree(stolen);
+	return;
+}
+
 struct drm_i915_gem_object *
 i915_gem_object_create_stolen_for_preallocated(struct drm_device *dev,
 					       u32 stolen_offset,
-- 
1.8.5.2