On 04/30/2015 12:19 PM, Joonas Lahtinen wrote:

GGTT VMA sizes might be smaller than the whole object size due to
different GGTT views.

v2:
- Separate GGTT view constraint calculations from normal view
   constraint calculations (Chris Wilson)
v3:
- Do not bother with debug wording. (Tvrtko Ursulin)

Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
---
  drivers/gpu/drm/i915/i915_gem.c     | 103 +++++++++++++++++++++++-------------
  drivers/gpu/drm/i915/i915_gem_gtt.c |  23 ++++++++
  drivers/gpu/drm/i915/i915_gem_gtt.h |   4 ++
  3 files changed, 92 insertions(+), 38 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e8f6f4c..9717c9d 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3497,7 +3497,8 @@ static bool i915_gem_valid_gtt_space(struct i915_vma *vma,
  }

  /**
- * Finds free space in the GTT aperture and binds the object there.
+ * Finds free space in the GTT aperture and binds the object or a view of it
+ * there.
   */
  static struct i915_vma *
  i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
@@ -3516,36 +3517,60 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object 
*obj,
        struct i915_vma *vma;
        int ret;

-       if(WARN_ON(i915_is_ggtt(vm) != !!ggtt_view))
-               return ERR_PTR(-EINVAL);
+       if (i915_is_ggtt(vm)) {
+               u32 view_size;
+
+               if (WARN_ON(!ggtt_view))
+                       return ERR_PTR(-EINVAL);

-       fence_size = i915_gem_get_gtt_size(dev,
-                                          obj->base.size,
-                                          obj->tiling_mode);
-       fence_alignment = i915_gem_get_gtt_alignment(dev,
-                                                    obj->base.size,
-                                                    obj->tiling_mode, true);
-       unfenced_alignment =
-               i915_gem_get_gtt_alignment(dev,
-                                          obj->base.size,
-                                          obj->tiling_mode, false);
+               view_size = i915_ggtt_view_size(obj, ggtt_view);
+
+               fence_size = i915_gem_get_gtt_size(dev,
+                                                  view_size,
+                                                  obj->tiling_mode);
+               fence_alignment = i915_gem_get_gtt_alignment(dev,
+                                                            view_size,
+                                                            obj->tiling_mode,
+                                                            true);
+               unfenced_alignment = i915_gem_get_gtt_alignment(dev,
+                                                               view_size,
+                                                               
obj->tiling_mode,
+                                                               false);
+               size = flags & PIN_MAPPABLE ? fence_size : view_size;
+       } else {
+               fence_size = i915_gem_get_gtt_size(dev,
+                                                  obj->base.size,
+                                                  obj->tiling_mode);
+               fence_alignment = i915_gem_get_gtt_alignment(dev,
+                                                            obj->base.size,
+                                                            obj->tiling_mode,
+                                                            true);
+               unfenced_alignment =
+                       i915_gem_get_gtt_alignment(dev,
+                                                  obj->base.size,
+                                                  obj->tiling_mode,
+                                                  false);
+               size = flags & PIN_MAPPABLE ? fence_size : obj->base.size;
+       }

I do not like this almost identical branches - so I defer to Chris to okay that this is what he wanted.

        if (alignment == 0)
                alignment = flags & PIN_MAPPABLE ? fence_alignment :
                                                unfenced_alignment;
        if (flags & PIN_MAPPABLE && alignment & (fence_alignment - 1)) {
-               DRM_DEBUG("Invalid object alignment requested %u\n", alignment);
+               DRM_DEBUG("Invalid object (view type=%u) alignment requested 
%u\n",
+                         ggtt_view ? ggtt_view->type : 0,
+                         alignment);
                return ERR_PTR(-EINVAL);
        }

-       size = flags & PIN_MAPPABLE ? fence_size : obj->base.size;
-
-       /* If the object is bigger than the entire aperture, reject it early
-        * before evicting everything in a vain attempt to find space.
+       /* If binding the object/GGTT view requires more space than the entire
+        * aperture has, reject it early before evicting everything in a vain
+        * attempt to find space.
         */
-       if (obj->base.size > end) {
-               DRM_DEBUG("Attempting to bind an object larger than the aperture: 
object=%zd > %s aperture=%lu\n",
-                         obj->base.size,
+       if (size > end) {
+               DRM_DEBUG("Attempting to bind an object (view type=%u) larger than the 
aperture: size=%u > %s aperture=%lu\n",
+                         ggtt_view ? ggtt_view->type : 0,
+                         size,
                          flags & PIN_MAPPABLE ? "mappable" : "total",
                          end);
                return ERR_PTR(-E2BIG);
@@ -4207,28 +4232,30 @@ i915_gem_object_do_pin(struct drm_i915_gem_object *obj,
                        return ret;
        }

-       if ((bound ^ vma->bound) & GLOBAL_BIND) {
-               bool mappable, fenceable;
-               u32 fence_size, fence_alignment;
+       if (!ggtt_view || ggtt_view->type == I915_GGTT_VIEW_NORMAL) {
+               if ((bound ^ vma->bound) & GLOBAL_BIND) {

I still don't get this. !ggtt_view means GLOBAL_BIND cannot be set, what am I missing? It wouldn't work if the condition was just the type check?

+                       bool mappable, fenceable;
+                       u32 fence_size, fence_alignment;

-               fence_size = i915_gem_get_gtt_size(obj->base.dev,
-                                                  obj->base.size,
-                                                  obj->tiling_mode);
-               fence_alignment = i915_gem_get_gtt_alignment(obj->base.dev,
-                                                            obj->base.size,
-                                                            obj->tiling_mode,
-                                                            true);
+                       fence_size = i915_gem_get_gtt_size(obj->base.dev,
+                                                          obj->base.size,
+                                                          obj->tiling_mode);
+                       fence_alignment = 
i915_gem_get_gtt_alignment(obj->base.dev,
+                                                                    
obj->base.size,
+                                                                    
obj->tiling_mode,
+                                                                    true);

-               fenceable = (vma->node.size == fence_size &&
-                            (vma->node.start & (fence_alignment - 1)) == 0);
+                       fenceable = (vma->node.size == fence_size &&
+                                    (vma->node.start & (fence_alignment - 1)) 
== 0);

-               mappable = (vma->node.start + fence_size <=
-                           dev_priv->gtt.mappable_end);
+                       mappable = (vma->node.start + fence_size <=
+                                   dev_priv->gtt.mappable_end);

-               obj->map_and_fenceable = mappable && fenceable;
-       }
+                       obj->map_and_fenceable = mappable && fenceable;
+               }

-       WARN_ON(flags & PIN_MAPPABLE && !obj->map_and_fenceable);
+               WARN_ON(flags & PIN_MAPPABLE && !obj->map_and_fenceable);
+       }

        vma->pin_count++;
        return 0;
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c 
b/drivers/gpu/drm/i915/i915_gem_gtt.c
index fc562c6..640584f 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2847,3 +2847,26 @@ int i915_vma_bind(struct i915_vma *vma, enum 
i915_cache_level cache_level,

        return 0;
  }
+
+/**
+ * i915_ggtt_view_size - Get the size of a GGTT view.
+ * @obj: Object the view is of.
+ * @view: The view in question.
+ *
+ * @return The size of the GGTT view in bytes.
+ */
+size_t
+i915_ggtt_view_size(struct drm_i915_gem_object *obj,
+                   const struct i915_ggtt_view *view)
+{
+       BUG_ON(!view);

It is a marginal point, but I wonder is size zero could be considered as a failure value and acted upon from the caller more gracefuly.

And in general I wonder if something like I915_BUG_ON which would re-route fops to fail-all and grab struct_mutex, or something, would maybe be an option.

Regards,

Tvrtko
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