drm/omap: use __GFP_DMA32 for shmem-backed gem

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.

Reviewed-by: Rob Clark <robdclark@gmail.com>
Tested-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 95dbce286a41..1331fd538398 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;