[PATCH 2/4] drm/prime: document that use the page array is deprecated
From: Christian König
Date: Thu Oct 08 2020 - 07:24:11 EST
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@xxxxxxx>
---
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.
*/
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