drm/i915: Add a partial GGTT view type

Partial view type allows manipulating parts of huge BOs through the GGTT,
which was not previously possible due to constraint that whole object had
to be mapped for any access to it through GGTT.

v2:
- Retain error value from sg_alloc_table (Tvrtko Ursulin)
- Do not zero already zeroed variable (Tvrtko Ursulin)
- Use more common variable types for page size/offset (Tvrtko Ursulin)
v3:
- Only compare additional view parameters when need to (Tvrtko Ursulin)
v4:
- Do zero out the variable that needs to be (bug introduced in v2).

Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 2b7c77b987bc3c5ae442f62f5e3c5efc00bee17a..e3bcc3ba7e405f28dd764752ba72d941222ccb20 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2753,6 +2753,47 @@ err_st_alloc:
        return ERR_PTR(ret);
 }
 
+static struct sg_table *
+intel_partial_pages(const struct i915_ggtt_view *view,
+                   struct drm_i915_gem_object *obj)
+{
+       struct sg_table *st;
+       struct scatterlist *sg;
+       struct sg_page_iter obj_sg_iter;
+       int ret = -ENOMEM;
+
+       st = kmalloc(sizeof(*st), GFP_KERNEL);
+       if (!st)
+               goto err_st_alloc;
+
+       ret = sg_alloc_table(st, view->params.partial.size, GFP_KERNEL);
+       if (ret)
+               goto err_sg_alloc;
+
+       sg = st->sgl;
+       st->nents = 0;
+       for_each_sg_page(obj->pages->sgl, &obj_sg_iter, obj->pages->nents,
+               view->params.partial.offset)
+       {
+               if (st->nents >= view->params.partial.size)
+                       break;
+
+               sg_set_page(sg, NULL, PAGE_SIZE, 0);
+               sg_dma_address(sg) = sg_page_iter_dma_address(&obj_sg_iter);
+               sg_dma_len(sg) = PAGE_SIZE;
+
+               sg = sg_next(sg);
+               st->nents++;
+       }
+
+       return st;
+
+err_sg_alloc:
+       kfree(st);
+err_st_alloc:
+       return ERR_PTR(ret);
+}
+
 static int
 i915_get_ggtt_vma_pages(struct i915_vma *vma)
 {
@@ -2766,6 +2807,9 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma)
        else if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED)
                vma->ggtt_view.pages =
                        intel_rotate_fb_obj_pages(&vma->ggtt_view, vma->obj);
+       else if (vma->ggtt_view.type == I915_GGTT_VIEW_PARTIAL)
+               vma->ggtt_view.pages =
+                       intel_partial_pages(&vma->ggtt_view, vma->obj);
        else
                WARN_ONCE(1, "GGTT view %u not implemented!\n",
                          vma->ggtt_view.type);
@@ -2853,6 +2897,8 @@ i915_ggtt_view_size(struct drm_i915_gem_object *obj,
        if (view->type == I915_GGTT_VIEW_NORMAL ||
            view->type == I915_GGTT_VIEW_ROTATED) {
                return obj->base.size;
+       } else if (view->type == I915_GGTT_VIEW_PARTIAL) {
+               return view->params.partial.size << PAGE_SHIFT;
        } else {
                WARN_ONCE(1, "GGTT view %u not implemented!\n", view->type);
                return obj->base.size;

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 34b7cca3df131aff2a8c4979d514e445301c1169..0d46dd20bf717507fddbf22830e053322d399f32 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -117,7 +117,8 @@ typedef uint64_t gen8_pde_t;
 
 enum i915_ggtt_view_type {
        I915_GGTT_VIEW_NORMAL = 0,
-       I915_GGTT_VIEW_ROTATED
+       I915_GGTT_VIEW_ROTATED,
+       I915_GGTT_VIEW_PARTIAL,
 };
 
 struct intel_rotation_info {
@@ -130,6 +131,13 @@ struct intel_rotation_info {
 struct i915_ggtt_view {
        enum i915_ggtt_view_type type;
 
+       union {
+               struct {
+                       unsigned long offset;
+                       unsigned int size;
+               } partial;
+       } params;
+
        struct sg_table *pages;
 
        union {
@@ -495,7 +503,11 @@ i915_ggtt_view_equal(const struct i915_ggtt_view *a,
        if (WARN_ON(!a || !b))
                return false;
 
-       return a->type == b->type;
+       if (a->type != b->type)
+               return false;
+       if (a->type == I915_GGTT_VIEW_PARTIAL)
+               return !memcmp(&a->params, &b->params, sizeof(a->params));
+       return true;
 }
 
 size_t