Re: [PATCH v3 2/7] drm/ttm: Add ttm_kmap_obj_to_dma_buf_map() for type conversion

Daniel Vetter
2020-09-29T15:45:00Z

On Tue, Sep 29, 2020 at 5:35 PM Christian König
<christian.koenig@amd.com> wrote:
>
> Am 29.09.20 um 17:14 schrieb Thomas Zimmermann:
> > The new helper ttm_kmap_obj_to_dma_buf() extracts address and location
> > from and instance of TTM's kmap_obj and initializes struct dma_buf_map
> > with these values. Helpful for TTM-based drivers.
>
> We could completely drop that if we use the same structure inside TTM as
> well.

> Additional to that which driver is going to use this?

Patch 3 in this series.

I also think this makes sense for gradual conversion:
1. add this helper
2. convert over all users of vmap, this should get rid of is_iomem
flags (and will probably result in a pile of small additions to
dma-buf-map.h)
3. push the struct dma_buf_map down into ttm drivers

Cheers, Daniel

> Regards,
> Christian.
>
> >
> > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> > ---
> > include/drm/ttm/ttm_bo_api.h | 24 ++++++++++++++++++++++++
> > include/linux/dma-buf-map.h | 20 ++++++++++++++++++++
> > 2 files changed, 44 insertions(+)
> >
> > diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> > index c96a25d571c8..62d89f05a801 100644
> > --- a/include/drm/ttm/ttm_bo_api.h
> > +++ b/include/drm/ttm/ttm_bo_api.h
> > @@ -34,6 +34,7 @@
> > #include <drm/drm_gem.h>
> > #include <drm/drm_hashtab.h>
> > #include <drm/drm_vma_manager.h>
> > +#include <linux/dma-buf-map.h>
> > #include <linux/kref.h>
> > #include <linux/list.h>
> > #include <linux/wait.h>
> > @@ -486,6 +487,29 @@ static inline void *ttm_kmap_obj_virtual(struct ttm_bo_kmap_obj *map,
> > return map->virtual;
> > }
> >
> > +/**
> > + * ttm_kmap_obj_to_dma_buf_map
> > + *
> > + * @kmap: A struct ttm_bo_kmap_obj returned from ttm_bo_kmap.
> > + * @map: Returns the mapping as struct dma_buf_map
> > + *
> > + * Converts struct ttm_bo_kmap_obj to struct dma_buf_map. If the memory
> > + * is not mapped, the returned mapping is initialized to NULL.
> > + */
> > +static inline void ttm_kmap_obj_to_dma_buf_map(struct ttm_bo_kmap_obj *kmap,
> > + struct dma_buf_map *map)
> > +{
> > + bool is_iomem;
> > + void *vaddr = ttm_kmap_obj_virtual(kmap, &is_iomem);
> > +
> > + if (!vaddr)
> > + dma_buf_map_clear(map);
> > + else if (is_iomem)
> > + dma_buf_map_set_vaddr_iomem(map, (void __force __iomem *)vaddr);
> > + else
> > + dma_buf_map_set_vaddr(map, vaddr);
> > +}
> > +
> > /**
> > * ttm_bo_kmap
> > *
> > diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h
> > index fd1aba545fdf..2e8bbecb5091 100644
> > --- a/include/linux/dma-buf-map.h
> > +++ b/include/linux/dma-buf-map.h
> > @@ -45,6 +45,12 @@
> > *
> > * dma_buf_map_set_vaddr(&map. 0xdeadbeaf);
> > *
> > + * To set an address in I/O memory, use dma_buf_map_set_vaddr_iomem().
> > + *
> > + * .. code-block:: c
> > + *
> > + * dma_buf_map_set_vaddr_iomem(&map. 0xdeadbeaf);
> > + *
> > * Test if a mapping is valid with either dma_buf_map_is_set() or
> > * dma_buf_map_is_null().
> > *
> > @@ -118,6 +124,20 @@ static inline void dma_buf_map_set_vaddr(struct dma_buf_map *map, void *vaddr)
> > map->is_iomem = false;
> > }
> >
> > +/**
> > + * dma_buf_map_set_vaddr_iomem - Sets a dma-buf mapping structure to an address in I/O memory
> > + * @map: The dma-buf mapping structure
> > + * @vaddr_iomem: An I/O-memory address
> > + *
> > + * Sets the address and the I/O-memory flag.
> > + */
> > +static inline void dma_buf_map_set_vaddr_iomem(struct dma_buf_map *map,
> > + void __iomem *vaddr_iomem)
> > +{
> > + map->vaddr_iomem = vaddr_iomem;
> > + map->is_iomem = true;
> > +}
> > +
> > /**
> > * dma_buf_map_is_equal - Compares two dma-buf mapping structures for equality
> > * @lhs: The dma-buf mapping structure
>

--
Daniel Vetter
Software Engineer, Intel Corporation