On Thu, Oct 08, 2020 at 04:09:14PM +0200, Daniel Vetter wrote:
On Thu, Oct 08, 2020 at 01:23:40PM +0200, Christian König wrote:
We have reoccurring requests on this so better document that this approach doesn't work and dma_buf_mmap() needs to be used instead.
Signed-off-by: Christian König christian.koenig@amd.com
drivers/gpu/drm/drm_prime.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index 4910c446db83..16fa2bfc271e 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -956,7 +956,7 @@ EXPORT_SYMBOL(drm_gem_prime_import); /**
- drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
- @sgt: scatter-gather table to convert
- @pages: optional array of page pointers to store the page array in
- @pages: deprecated array of page pointers to store the page array in
- @addrs: optional array to store the dma bus address of each page
- @max_entries: size of both the passed-in arrays
@@ -965,6 +965,11 @@ EXPORT_SYMBOL(drm_gem_prime_import);
- Drivers can use this in their &drm_driver.gem_prime_import_sg_table
- implementation.
- Specifying the pages array is deprecated and strongly discouraged for new
- drivers. The pages array is only useful for page faults and those can
- corrupt fields in the struct page if they are not handled by the exporting
*/
- driver.
I'd make this a _lot_ stronger: Aside from amdgpu and radeon all drivers using this only need it for the pages array. Imo just open-code the sg table walking loop in amdgpu/radeon (it's really not much code), and then drop the dma_addr_t parameter from this function here (it's set to NULL by everyone else).
And then deprecate this entire function here with a big warning that a) dma_buf_map_attachment is allowed to leave the struct page pointers NULL and b) this breaks mmap, users must call dma_buf_mmap instead.
Also maybe make it an uppercase DEPRECATED or something like that :-)
OK I just realized I missed nouveau. That would be 3 places where we need to stuff the dma_addr_t list into something ttm can take. Still feels better than this half-deprecated function kludge ... -Daniel
-Daniel
int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages, dma_addr_t *addrs, int max_entries) -- 2.17.1
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch