drm/i915: Avoid clearing preallocated regions from the GTT

As yet we do not do any preallocation (chicken-and-egg problem), but we
may like to preserve anything already allocated by the BIOS or grub and
reuse for own purposes after initialising the driver.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 21360a7..f16101f 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -935,6 +935,8 @@ 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 f7ac61e..cc1be53 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -531,20 +531,46 @@ 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;
+       unsigned long hole_start, hole_end;
 
-       /* 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. */
-       i915_ggtt_clear_range(dev, start / PAGE_SIZE, (end-start) / PAGE_SIZE);
+       /* Clear any non-preallocated blocks */
+       drm_mm_for_each_hole(entry, &dev_priv->mm.gtt_space,
+                            hole_start, hole_end) {
+               DRM_DEBUG_KMS("clearing unused GTT space: [%lx, %lx]\n",
+                             hole_start, hole_end);
+               i915_ggtt_clear_range(dev,
+                                     hole_start / PAGE_SIZE,
+                                     (hole_end-hole_start) / PAGE_SIZE);
+       }
+
+       /* And finally clear the reserved guard page */
+       i915_ggtt_clear_range(dev, end / PAGE_SIZE - 1, 1);
 }
 
 static int setup_scratch_page(struct drm_device *dev)