[PATCH 04/18] drm/i915: Avoid clearing preallocated regions from the GTT

Chris Wilson
2012-10-19T17:05:02Z

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
drivers/gpu/drm/i915/i915_drv.h | 2 ++
drivers/gpu/drm/i915/i915_gem_gtt.c | 35 ++++++++++++++++++++++++++++++++---
2 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 687f379..589b2f3 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -908,6 +908,8 @@ enum i915_cache_level {
I915_CACHE_LLC_MLC, /* gen6+, in docs at least! */
};

+#define I915_GTT_RESERVED ((struct drm_mm_node *)0x1)
+
struct drm_i915_gem_object_ops {
/* Interface between the GEM object and its backing storage.
* get_pages() is called once prior to the use of the associated set
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 47e427e..d9d3fc7 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -378,18 +378,47 @@ void i915_gem_init_global_gtt(struct drm_device *dev,
unsigned long end)
{
drm_i915_private_t *dev_priv = dev->dev_private;
+ struct drm_mm_node *entry;
+ struct drm_i915_gem_object *obj;

- /* Substract the guard page ... */
+ /* Subtract the guard page ... */
drm_mm_init(&dev_priv->mm.gtt_space, start, end - start - PAGE_SIZE);
if (!HAS_LLC(dev))
dev_priv->mm.gtt_space.color_adjust = i915_gtt_color_adjust;

+ /* Mark any preallocated objects as occupied */
+ list_for_each_entry(obj, &dev_priv->mm.bound_list, gtt_list) {
+ DRM_DEBUG_KMS("reserving preallocated space: %x + %zx\n",
+ obj->gtt_offset, obj->base.size);
+
+ BUG_ON(obj->gtt_space != I915_GTT_RESERVED);
+ obj->gtt_space = drm_mm_create_block(&dev_priv->mm.gtt_space,
+ obj->gtt_offset,
+ obj->base.size,
+ false);
+ obj->has_global_gtt_mapping = 1;
+ }
+
dev_priv->mm.gtt_start = start;
dev_priv->mm.gtt_mappable_end = mappable_end;
dev_priv->mm.gtt_end = end;
dev_priv->mm.gtt_total = end - start;
dev_priv->mm.mappable_gtt_total = min(end, mappable_end) - start;

- /* ... but ensure that we clear the entire range. */
- intel_gtt_clear_range(start / PAGE_SIZE, (end-start) / PAGE_SIZE);
+ /* Clear any non-preallocated blocks */
+ list_for_each_entry(entry, &dev_priv->mm.gtt_space.hole_stack, hole_stack) {
+ unsigned long hole_start = entry->start + entry->size;
+ unsigned long hole_end = list_entry(entry->node_list.next,
+ struct drm_mm_node,
+ node_list)->start;
+
+ DRM_DEBUG_KMS("clearing unused GTT space: [%lx, %lx]\n",
+ hole_start, hole_end);
+
+ intel_gtt_clear_range(hole_start / PAGE_SIZE,
+ (hole_end-hole_start) / PAGE_SIZE);
+ }
+
+ /* And finally clear the reserved guard page */
+ intel_gtt_clear_range(end / PAGE_SIZE - 1, 1);
}
--
1.7.10.4