Commit 718370ff authored by Jocelyn Falempe's avatar Jocelyn Falempe Committed by Maarten Lankhorst
Browse files

drm/ttm: Add ttm_bo_kmap_try_from_panic() 



If the ttm bo is backed by pages, then it's possible to safely kmap
one page at a time, using kmap_try_from_panic().
Unfortunately there is no way to do the same with ioremap, so it
only supports the kmap case.
This is needed for proper drm_panic support with xe driver.

Signed-off-by: default avatarJocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20250624091501.257661-6-jfalempe@redhat.com


Signed-off-by: default avatarMaarten Lankhorst <dev@lankhorst.se>
parent 796f437d

drivers/gpu/drm/ttm/ttm_bo_util.c

+27 −0
Original line number Diff line number Diff line
@@ -381,6 +381,33 @@ static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo, 
	return (!map->virtual) ? -ENOMEM : 0;

}



/**

 *

 * ttm_bo_kmap_try_from_panic

 *

 * @bo: The buffer object

 * @page: The page to map

 *

 * Sets up a kernel virtual mapping using kmap_local_page_try_from_panic().

 * This should only be called from the panic handler, if you make sure the bo

 * is the one being displayed, so is properly allocated, and protected.

 *

 * Returns the vaddr, that you can use to write to the bo, and that you should

 * pass to kunmap_local() when you're done with this page, or NULL if the bo

 * is in iomem.

 */

void *ttm_bo_kmap_try_from_panic(struct ttm_buffer_object *bo, unsigned long page)

{

	if (page + 1 > PFN_UP(bo->resource->size))

		return NULL;



	if (!bo->resource->bus.is_iomem && bo->ttm->pages && bo->ttm->pages[page])

		return kmap_local_page_try_from_panic(bo->ttm->pages[page]);



	return NULL;

}

EXPORT_SYMBOL(ttm_bo_kmap_try_from_panic);



/**

 * ttm_bo_kmap

 *

include/drm/ttm/ttm_bo.h

+1 −0
Original line number Diff line number Diff line
@@ -401,6 +401,7 @@ int ttm_bo_init_validate(struct ttm_device *bdev, struct ttm_buffer_object *bo, 
int ttm_bo_kmap(struct ttm_buffer_object *bo, unsigned long start_page,

		unsigned long num_pages, struct ttm_bo_kmap_obj *map);

void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map);

void *ttm_bo_kmap_try_from_panic(struct ttm_buffer_object *bo, unsigned long page);

int ttm_bo_vmap(struct ttm_buffer_object *bo, struct iosys_map *map);

void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct iosys_map *map);

int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo);