[Intel-gfx] [PATCH v4 3/8] drm/i915: Add a new "remapped" gtt_view

Ville Syrjälä ville.syrjala at linux.intel.com
Tue Oct 23 19:10:48 UTC 2018


On Tue, Oct 23, 2018 at 07:56:58PM +0100, Chris Wilson wrote:
> Quoting Ville Syrjala (2018-10-23 17:02:36)
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > To overcome display engine stride limits we'll want to remap the
> > pages in the GTT. To that end we need a new gtt_view type which
> > is just like the "rotated" type except not rotated.
> > 
> > v2: Use intel_remapped_plane_info base type
> >     s/unused/unused_mbz/ (Chris)
> >     Separate BUILD_BUG_ON()s (Chris)
> >     Use I915_GTT_PAGE_SIZE (Chris)
> > v3: Use i915_gem_object_get_dma_address() (Chris)
> >     Trim the sg (Tvrtko)
> > 
> > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_debugfs.c       | 12 ++++
> >  drivers/gpu/drm/i915/i915_gem_gtt.c       | 74 +++++++++++++++++++++++
> >  drivers/gpu/drm/i915/i915_gem_gtt.h       | 25 ++++++--
> >  drivers/gpu/drm/i915/i915_vma.c           |  6 +-
> >  drivers/gpu/drm/i915/i915_vma.h           |  3 +
> >  drivers/gpu/drm/i915/intel_display.c      | 11 ++++
> >  drivers/gpu/drm/i915/intel_drv.h          |  1 +
> >  drivers/gpu/drm/i915/selftests/i915_vma.c |  6 +-
> >  8 files changed, 130 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> > index 5b37d5f8e132..ce019126304d 100644
> > --- a/drivers/gpu/drm/i915/i915_debugfs.c
> > +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> > @@ -196,6 +196,18 @@ describe_obj(struct seq_file *m, struct drm_i915_gem_object *obj)
> >                                            vma->ggtt_view.rotated.plane[1].offset);
> >                                 break;
> >  
> > +                       case I915_GGTT_VIEW_REMAPPED:
> > +                               seq_printf(m, ", remapped [(%ux%u, stride=%u, offset=%u), (%ux%u, stride=%u, offset=%u)]",
> > +                                          vma->ggtt_view.remapped.plane[0].width,
> > +                                          vma->ggtt_view.remapped.plane[0].height,
> > +                                          vma->ggtt_view.remapped.plane[0].stride,
> > +                                          vma->ggtt_view.remapped.plane[0].offset,
> > +                                          vma->ggtt_view.remapped.plane[1].width,
> > +                                          vma->ggtt_view.remapped.plane[1].height,
> > +                                          vma->ggtt_view.remapped.plane[1].stride,
> > +                                          vma->ggtt_view.remapped.plane[1].offset);
> > +                               break;
> > +
> >                         default:
> >                                 MISSING_CASE(vma->ggtt_view.type);
> >                                 break;
> > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > index 98d9a1eb1ed2..d0e50b584ebd 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_gtt.c
> > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
> > @@ -3705,6 +3705,75 @@ intel_rotate_pages(struct intel_rotation_info *rot_info,
> >         return ERR_PTR(ret);
> >  }
> >  
> > +static struct scatterlist *
> > +remap_pages(struct drm_i915_gem_object *obj, unsigned int offset,
> > +           unsigned int width, unsigned int height,
> > +           unsigned int stride,
> > +           struct sg_table *st, struct scatterlist *sg)
> > +{
> > +       unsigned int column, row;
> > +
> > +       for (row = 0; row < height; row++) {
> > +               for (column = 0; column < width; column++) {
> > +                       st->nents++;
> > +                       /* We don't need the pages, but need to initialize
> > +                        * the entries so the sg list can be happily traversed.
> > +                        * The only thing we need are DMA addresses.
> > +                        */
> > +                       sg_set_page(sg, NULL, I915_GTT_PAGE_SIZE, 0);
> > +                       sg_dma_address(sg) =
> > +                               i915_gem_object_get_dma_address(obj, offset + column);
> > +                       sg_dma_len(sg) = I915_GTT_PAGE_SIZE;
> 
> There's a bit of work that we could apply here with
> i915_gem_object_get_sg() and try and keep large spans. Probably not very
> important given that this is for GGTT and so not supporting large PTE,
> so we only loose out on keeping the vma->pages sg as small as possible.
> 
> > +                       sg = sg_next(sg);
> > +               }
> > +               offset += stride;
> > +       }
> > +
> > +       return sg;
> > +}
> > +
> > +static noinline struct sg_table *
> > +intel_remap_pages(struct intel_remapped_info *rem_info,
> > +                 struct drm_i915_gem_object *obj)
> > +{
> > +       unsigned int size = intel_remapped_info_size(rem_info);
> > +       struct sg_table *st;
> > +       struct scatterlist *sg;
> > +       int ret = -ENOMEM;
> > +       int i;
> > +
> > +       /* Allocate target SG list. */
> > +       st = kmalloc(sizeof(*st), GFP_KERNEL);
> > +       if (!st)
> > +               goto err_st_alloc;
> > +
> > +       ret = sg_alloc_table(st, size, GFP_KERNEL);
> > +       if (ret)
> > +               goto err_sg_alloc;
> > +
> > +       st->nents = 0;
> > +       sg = st->sgl;
> > +
> > +       for (i = 0 ; i < ARRAY_SIZE(rem_info->plane); i++) {
> > +               sg = remap_pages(obj, rem_info->plane[i].offset,
> > +                                rem_info->plane[i].width, rem_info->plane[i].height,
> > +                                rem_info->plane[i].stride, st, sg);
> > +       }
> > +
> > +       i915_sg_trim(st);
> > +
> > +       return st;
> > +
> > +err_sg_alloc:
> > +       kfree(st);
> > +err_st_alloc:
> > +
> > +       DRM_DEBUG_DRIVER("Failed to create remapped mapping for object size %zu! (%ux%u tiles, %u pages)\n",
> > +                        obj->base.size, rem_info->plane[0].width, rem_info->plane[0].height, size);
> > +
> > +       return ERR_PTR(ret);
> > +}
> > +
> >  static noinline struct sg_table *
> >  intel_partial_pages(const struct i915_ggtt_view *view,
> >                     struct drm_i915_gem_object *obj)
> > @@ -3783,6 +3852,11 @@ i915_get_ggtt_vma_pages(struct i915_vma *vma)
> >                         intel_rotate_pages(&vma->ggtt_view.rotated, vma->obj);
> >                 break;
> >  
> > +       case I915_GGTT_VIEW_REMAPPED:
> > +               vma->pages =
> > +                       intel_remap_pages(&vma->ggtt_view.remapped, vma->obj);
> > +               break;
> > +
> >         case I915_GGTT_VIEW_PARTIAL:
> >                 vma->pages = intel_partial_pages(&vma->ggtt_view, vma->obj);
> >                 break;
> > diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> > index 7e2af5f4f39b..69a22f57e6ca 100644
> > --- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> > +++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> > @@ -160,11 +160,18 @@ typedef u64 gen8_ppgtt_pml4e_t;
> >  
> >  struct sg_table;
> >  
> > +struct intel_remapped_plane_info {
> > +       /* in gtt pages */
> > +       unsigned int width, height, stride, offset;
> > +} __packed;
> > +
> > +struct intel_remapped_info {
> > +       struct intel_remapped_plane_info plane[2];
> > +       unsigned int unused_mbz;
> > +} __packed;
> > +
> >  struct intel_rotation_info {
> > -       struct intel_rotation_plane_info {
> > -               /* tiles */
> > -               unsigned int width, height, stride, offset;
> > -       } plane[2];
> > +       struct intel_remapped_plane_info plane[2];
> >  } __packed;
> >  
> >  struct intel_partial_info {
> > @@ -176,12 +183,20 @@ enum i915_ggtt_view_type {
> >         I915_GGTT_VIEW_NORMAL = 0,
> >         I915_GGTT_VIEW_ROTATED = sizeof(struct intel_rotation_info),
> >         I915_GGTT_VIEW_PARTIAL = sizeof(struct intel_partial_info),
> > +       I915_GGTT_VIEW_REMAPPED = sizeof(struct intel_remapped_info),
> >  };
> >  
> >  static inline void assert_i915_gem_gtt_types(void)
> >  {
> >         BUILD_BUG_ON(sizeof(struct intel_rotation_info) != 8*sizeof(unsigned int));
> >         BUILD_BUG_ON(sizeof(struct intel_partial_info) != sizeof(u64) + sizeof(unsigned int));
> > +       BUILD_BUG_ON(sizeof(struct intel_remapped_info) != 9*sizeof(unsigned int));
> > +
> > +       /* Check that rotation/remapped shares offsets for simplicity */
> > +       BUILD_BUG_ON(offsetof(struct intel_remapped_info, plane[0]) !=
> > +                    offsetof(struct intel_rotation_info, plane[0]));
> > +       BUILD_BUG_ON(offsetofend(struct intel_remapped_info, plane[1]) !=
> > +                    offsetofend(struct intel_rotation_info, plane[1]));
> >  
> >         /* As we encode the size of each branch inside the union into its type,
> >          * we have to be careful that each branch has a unique size.
> > @@ -190,6 +205,7 @@ static inline void assert_i915_gem_gtt_types(void)
> >         case I915_GGTT_VIEW_NORMAL:
> >         case I915_GGTT_VIEW_PARTIAL:
> >         case I915_GGTT_VIEW_ROTATED:
> > +       case I915_GGTT_VIEW_REMAPPED:
> >                 /* gcc complains if these are identical cases */
> >                 break;
> >         }
> > @@ -201,6 +217,7 @@ struct i915_ggtt_view {
> >                 /* Members need to contain no holes/padding */
> >                 struct intel_partial_info partial;
> >                 struct intel_rotation_info rotated;
> > +               struct intel_remapped_info remapped;
> >         };
> >  };
> >  
> > diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
> > index 82652c3d1bed..2070e44eaa03 100644
> > --- a/drivers/gpu/drm/i915/i915_vma.c
> > +++ b/drivers/gpu/drm/i915/i915_vma.c
> > @@ -164,6 +164,9 @@ vma_create(struct drm_i915_gem_object *obj,
> >                 } else if (view->type == I915_GGTT_VIEW_ROTATED) {
> >                         vma->size = intel_rotation_info_size(&view->rotated);
> >                         vma->size <<= PAGE_SHIFT;
> > +               } else if (view->type == I915_GGTT_VIEW_REMAPPED) {
> > +                       vma->size = intel_remapped_info_size(&view->remapped);
> > +                       vma->size <<= PAGE_SHIFT;
> >                 }
> >         }
> >  
> > @@ -464,7 +467,8 @@ void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
> >          * Explicitly disable for rotated VMA since the display does not
> >          * need the fence and the VMA is not accessible to other users.
> >          */
> > -       if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED)
> > +       if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED ||
> > +           vma->ggtt_view.type == I915_GGTT_VIEW_REMAPPED)
> >                 return;
> 
> Hmm, still sure we don't want fences on the remapped view? Seems
> potentially useful.

I remove that restriction in the selftest patch since that's the first
thing that really needs it. I was pondering about moving it to an
entirely separate patch but for whatever reason decided against it.
I can still split it out if people prefer that?

>   
> >         fenceable = (vma->node.size >= vma->fence_size &&
> > diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
> > index 4f7c1c7599f4..64cf029c028a 100644
> > --- a/drivers/gpu/drm/i915/i915_vma.h
> > +++ b/drivers/gpu/drm/i915/i915_vma.h
> > @@ -265,8 +265,11 @@ i915_vma_compare(struct i915_vma *vma,
> >          */
> >         BUILD_BUG_ON(I915_GGTT_VIEW_NORMAL >= I915_GGTT_VIEW_PARTIAL);
> >         BUILD_BUG_ON(I915_GGTT_VIEW_PARTIAL >= I915_GGTT_VIEW_ROTATED);
> > +       BUILD_BUG_ON(I915_GGTT_VIEW_ROTATED >= I915_GGTT_VIEW_REMAPPED);
> >         BUILD_BUG_ON(offsetof(typeof(*view), rotated) !=
> >                      offsetof(typeof(*view), partial));
> > +       BUILD_BUG_ON(offsetof(typeof(*view), rotated) !=
> > +                    offsetof(typeof(*view), remapped));
> >         return memcmp(&vma->ggtt_view.partial, &view->partial, view->type);
> >  }
> >  
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 8a0b477a69d3..41f7e0795b14 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -1957,6 +1957,17 @@ unsigned int intel_rotation_info_size(const struct intel_rotation_info *rot_info
> >         return size;
> >  }
> >  
> > +unsigned int intel_remapped_info_size(const struct intel_remapped_info *rem_info)
> > +{
> > +       unsigned int size = 0;
> > +       int i;
> > +
> 
> I was looking for a good place to stick
> 	GEM_BUG_ON(rem_info->unused_mbz);
> Here?

I guess this as good a place as any. I shall add it.

> 
> > +       for (i = 0 ; i < ARRAY_SIZE(rem_info->plane); i++)
> > +               size += rem_info->plane[i].width * rem_info->plane[i].height;
> > +
> > +       return size;
> > +}
> > +
> >  static void
> >  intel_fill_fb_ggtt_view(struct i915_ggtt_view *view,
> >                         const struct drm_framebuffer *fb,
> > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > index 0e9a926fca04..6993eff5dfaf 100644
> > --- a/drivers/gpu/drm/i915/intel_drv.h
> > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > @@ -1523,6 +1523,7 @@ unsigned int intel_fb_xy_to_linear(int x, int y,
> >  void intel_add_fb_offsets(int *x, int *y,
> >                           const struct intel_plane_state *state, int plane);
> >  unsigned int intel_rotation_info_size(const struct intel_rotation_info *rot_info);
> > +unsigned int intel_remapped_info_size(const struct intel_remapped_info *rem_info);
> >  bool intel_has_pending_fb_unpin(struct drm_i915_private *dev_priv);
> >  void intel_mark_busy(struct drm_i915_private *dev_priv);
> >  void intel_mark_idle(struct drm_i915_private *dev_priv);
> > diff --git a/drivers/gpu/drm/i915/selftests/i915_vma.c b/drivers/gpu/drm/i915/selftests/i915_vma.c
> > index ffa74290e054..4fc49c27f13c 100644
> > --- a/drivers/gpu/drm/i915/selftests/i915_vma.c
> > +++ b/drivers/gpu/drm/i915/selftests/i915_vma.c
> > @@ -395,8 +395,8 @@ assert_rotated(struct drm_i915_gem_object *obj,
> >         return sg;
> >  }
> >  
> > -static unsigned int rotated_size(const struct intel_rotation_plane_info *a,
> > -                                const struct intel_rotation_plane_info *b)
> > +static unsigned int rotated_size(const struct intel_remapped_plane_info *a,
> > +                                const struct intel_remapped_plane_info *b)
> >  {
> >         return a->width * a->height + b->width * b->height;
> >  }
> > @@ -406,7 +406,7 @@ static int igt_vma_rotate(void *arg)
> >         struct drm_i915_private *i915 = arg;
> >         struct i915_address_space *vm = &i915->ggtt.vm;
> >         struct drm_i915_gem_object *obj;
> > -       const struct intel_rotation_plane_info planes[] = {
> > +       const struct intel_remapped_plane_info planes[] = {
> >                 { .width = 1, .height = 1, .stride = 1 },
> >                 { .width = 2, .height = 2, .stride = 2 },
> >                 { .width = 4, .height = 4, .stride = 4 },
> 
> The question on whether we do want fences here notwithstanding,
> Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
> -Chris

-- 
Ville Syrjälä
Intel


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