Commit bcc5c9d5 authored by Rob Clark's avatar Rob Clark Committed by Dave Airlie
Browse files

drm/gem: add shmem get/put page helpers 



Basically just extracting some code duplicated in gma500, omapdrm, udl,
and upcoming msm driver.

Signed-off-by: default avatarRob Clark <robdclark@gmail.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 367bbd49

drivers/gpu/drm/drm_gem.c

+103 −0
Original line number Diff line number Diff line
@@ -358,6 +358,109 @@ int drm_gem_create_mmap_offset(struct drm_gem_object *obj) 
}

EXPORT_SYMBOL(drm_gem_create_mmap_offset);



/**

 * drm_gem_get_pages - helper to allocate backing pages for a GEM object

 * from shmem

 * @obj: obj in question

 * @gfpmask: gfp mask of requested pages

 */

struct page **drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask)

{

	struct inode *inode;

	struct address_space *mapping;

	struct page *p, **pages;

	int i, npages;



	/* This is the shared memory object that backs the GEM resource */

	inode = file_inode(obj->filp);

	mapping = inode->i_mapping;



	/* We already BUG_ON() for non-page-aligned sizes in

	 * drm_gem_object_init(), so we should never hit this unless

	 * driver author is doing something really wrong:

	 */

	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);



	npages = obj->size >> PAGE_SHIFT;



	pages = drm_malloc_ab(npages, sizeof(struct page *));

	if (pages == NULL)

		return ERR_PTR(-ENOMEM);



	gfpmask |= mapping_gfp_mask(mapping);



	for (i = 0; i < npages; i++) {

		p = shmem_read_mapping_page_gfp(mapping, i, gfpmask);

		if (IS_ERR(p))

			goto fail;

		pages[i] = p;



		/* There is a hypothetical issue w/ drivers that require

		 * buffer memory in the low 4GB.. if the pages are un-

		 * pinned, and swapped out, they can end up swapped back

		 * in above 4GB.  If pages are already in memory, then

		 * shmem_read_mapping_page_gfp will ignore the gfpmask,

		 * even if the already in-memory page disobeys the mask.

		 *

		 * It is only a theoretical issue today, because none of

		 * the devices with this limitation can be populated with

		 * enough memory to trigger the issue.  But this BUG_ON()

		 * is here as a reminder in case the problem with

		 * shmem_read_mapping_page_gfp() isn't solved by the time

		 * it does become a real issue.

		 *

		 * See this thread: http://lkml.org/lkml/2011/7/11/238

		 */

		BUG_ON((gfpmask & __GFP_DMA32) &&

				(page_to_pfn(p) >= 0x00100000UL));

	}



	return pages;



fail:

	while (i--)

		page_cache_release(pages[i]);



	drm_free_large(pages);

	return ERR_CAST(p);

}

EXPORT_SYMBOL(drm_gem_get_pages);



/**

 * drm_gem_put_pages - helper to free backing pages for a GEM object

 * @obj: obj in question

 * @pages: pages to free

 * @dirty: if true, pages will be marked as dirty

 * @accessed: if true, the pages will be marked as accessed

 */

void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,

		bool dirty, bool accessed)

{

	int i, npages;



	/* We already BUG_ON() for non-page-aligned sizes in

	 * drm_gem_object_init(), so we should never hit this unless

	 * driver author is doing something really wrong:

	 */

	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);



	npages = obj->size >> PAGE_SHIFT;



	for (i = 0; i < npages; i++) {

		if (dirty)

			set_page_dirty(pages[i]);



		if (accessed)

			mark_page_accessed(pages[i]);



		/* Undo the reference we took when populating the table */

		page_cache_release(pages[i]);

	}



	drm_free_large(pages);

}

EXPORT_SYMBOL(drm_gem_put_pages);



/** Returns a reference to the object named by the handle. */

struct drm_gem_object *

drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,

include/drm/drmP.h

+4 −0
Original line number Diff line number Diff line
@@ -1616,6 +1616,10 @@ void drm_gem_free_mmap_offset(struct drm_gem_object *obj); 
int drm_gem_create_mmap_offset(struct drm_gem_object *obj);

int drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size);



struct page **drm_gem_get_pages(struct drm_gem_object *obj, gfp_t gfpmask);

void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,

		bool dirty, bool accessed);



struct drm_gem_object *drm_gem_object_lookup(struct drm_device *dev,

					     struct drm_file *filp,

					     u32 handle);