[PATCH 4/5] drm/omap: use __GFP_DMA32 for shmem-backed gem

[David Herrmann]

Hi Tomi

Any chance you could give this a spin on an omap device? It shouldn't
affect any 32bit devices, so this is mostly a cosmetic change.
However, I'd really like to get rid of that 'TODO' item. So a
"Tested-by:" would be really nice.

Thanks
David

On Sun, May 25, 2014 at 2:34 PM, David Herrmann <dh.herrmann at gmail.com> wrote:
> OMAP requires bo-pages to be in the DMA32 zone. Explicitly request this by
> setting __GFP_DMA32 as mapping-gfp-mask during shmem initialization. This
> drops HIGHMEM from the gfp-mask and uses DMA32 instead. shmem-core takes
> care to relocate pages during swap-in in case they have been loaded into
> the wrong zone.
>
> It is _not_ possible to pass __GFP_DMA32 to shmem_read_mapping_page_gfp()
> as the page might have already been swapped-in at that time. The zone-mask
> must be set during initialization and be kept constant for now.
>
> Remove the now superfluous TODO in omap_gem.c.
>
> Cc: Tomi Valkeinen <tomi.valkeinen at ti.com>
> Cc: Rob Clark <robdclark at gmail.com>
> Signed-off-by: David Herrmann <dh.herrmann at gmail.com>
> ---
>  drivers/gpu/drm/omapdrm/omap_gem.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
> index 95dbce2..1331fd5 100644
> --- a/drivers/gpu/drm/omapdrm/omap_gem.c
> +++ b/drivers/gpu/drm/omapdrm/omap_gem.c
> @@ -233,10 +233,6 @@ static int omap_gem_attach_pages(struct drm_gem_object *obj)
>
>         WARN_ON(omap_obj->pages);
>
> -       /* TODO: __GFP_DMA32 .. but somehow GFP_HIGHMEM is coming from the
> -        * mapping_gfp_mask(mapping) which conflicts w/ GFP_DMA32.. probably
> -        * we actually want CMA memory for it all anyways..
> -        */
>         pages = drm_gem_get_pages(obj, GFP_KERNEL);
>         if (IS_ERR(pages)) {
>                 dev_err(obj->dev->dev, "could not get pages: %ld\n", PTR_ERR(pages));
> @@ -1347,6 +1343,7 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
>         struct omap_drm_private *priv = dev->dev_private;
>         struct omap_gem_object *omap_obj;
>         struct drm_gem_object *obj = NULL;
> +       struct address_space *mapping;
>         size_t size;
>         int ret;
>
> @@ -1404,14 +1401,16 @@ struct drm_gem_object *omap_gem_new(struct drm_device *dev,
>                 omap_obj->height = gsize.tiled.height;
>         }
>
> -       ret = 0;
> -       if (flags & (OMAP_BO_DMA|OMAP_BO_EXT_MEM))
> +       if (flags & (OMAP_BO_DMA|OMAP_BO_EXT_MEM)) {
>                 drm_gem_private_object_init(dev, obj, size);
> -       else
> +       } else {
>                 ret = drm_gem_object_init(dev, obj, size);
> +               if (ret)
> +                       goto fail;
>
> -       if (ret)
> -               goto fail;
> +               mapping = file_inode(obj->filp)->i_mapping;
> +               mapping_set_gfp_mask(mapping, GFP_USER | __GFP_DMA32);
> +       }
>
>         return obj;
>
> --
> 1.9.3
>