[Intel-gfx] [PATCH] drm/i915: Add TTM offset argument to mmap.

[Matthew Auld]

On Mon, 5 Jul 2021 at 15:36, Matthew Auld
<matthew.william.auld at gmail.com> wrote:
>
> On Thu, 1 Jul 2021 at 12:50, Maarten Lankhorst
> <maarten.lankhorst at linux.intel.com> wrote:
> >
> > Op 01-07-2021 om 13:42 schreef Maarten Lankhorst:
> > > This is only used for ttm, and tells userspace that the mapping type is
> > > ignored. This disables the other type of mmap offsets when discrete
> > > memory is used, so fix the selftests as well.
> > >
> > > Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/gem/i915_gem_mman.c      | 17 +++++++++++-
> > >  .../gpu/drm/i915/gem/i915_gem_object_types.h  |  1 +
> > >  .../drm/i915/gem/selftests/i915_gem_mman.c    | 27 +++++++++++++++++--
> > >  include/uapi/drm/i915_drm.h                   |  9 ++++---
> > >  4 files changed, 47 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> > > index a90f796e85c0..b34be9e5d094 100644
> > > --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> > > @@ -679,10 +679,16 @@ __assign_mmap_offset(struct drm_i915_gem_object *obj,
> > >               return -ENODEV;
> > >
> > >       if (obj->ops->mmap_offset)  {
> > > +             if (mmap_type != I915_MMAP_TYPE_TTM)
> > > +                     return -ENODEV;
> > > +
> > >               *offset = obj->ops->mmap_offset(obj);
> > >               return 0;
> > >       }
> > >
> > > +     if (mmap_type == I915_MMAP_TYPE_TTM)
> > > +             return -ENODEV;
> > > +
> > >       if (mmap_type != I915_MMAP_TYPE_GTT &&
> > >           !i915_gem_object_has_struct_page(obj) &&
> > >           !i915_gem_object_has_iomem(obj))
> > > @@ -727,7 +733,9 @@ i915_gem_dumb_mmap_offset(struct drm_file *file,
> > >  {
> > >       enum i915_mmap_type mmap_type;
> > >
> > > -     if (boot_cpu_has(X86_FEATURE_PAT))
> > > +     if (HAS_LMEM(to_i915(dev)))
> > > +             mmap_type = I915_MMAP_TYPE_TTM;
> > > +     else if (boot_cpu_has(X86_FEATURE_PAT))
> > >               mmap_type = I915_MMAP_TYPE_WC;
>
> Hmm, I think we still need to check for X86_FEATURE_PAT somewhere,
> since this is still just WC for lmem?
>
> > >       else if (!i915_ggtt_has_aperture(&to_i915(dev)->ggtt))
> > >               return -ENODEV;
> > > @@ -798,6 +806,10 @@ i915_gem_mmap_offset_ioctl(struct drm_device *dev, void *data,
> > >               type = I915_MMAP_TYPE_UC;
> > >               break;
> > >
> > > +     case I915_MMAP_OFFSET_TTM:
> > > +             type = I915_MMAP_TYPE_TTM;
> > > +             break;
>
> Would it not be simpler to just convert to WC or WB here, if we
> encounter _TTM? With that we also don't need to touch the dumb mmap
> stuff and i915_gem_mmap()?
>
> if (IS_DGFX()) {
>         if (args->type != OFFSET_TTM)
>                return -ENODEV:
>
>        GEM_BUG_ON(!obj->mm.n_placements);
>        if (i915_gem_object_placement_possible(obj, INTEL_MEMORY_LOCAL)) {
>               type = TYPE_WC;
>       else
>               ttype = TYPE_WB;
> }
>
> https://patchwork.freedesktop.org/patch/442579/?series=92209&rev=1

fyi this patch is now merged, in case you need the
i915_gem_object_placement_possible() helper.