[PATCH 6/6] drm/prime: document that use the page array is deprecated v2
From: Christian König
Date: Fri Oct 09 2020 - 11:04:07 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.
v2: split it into two functions
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 9 ++-
drivers/gpu/drm/drm_prime.c | 67 +++++++++++++++------
drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c | 3 +-
drivers/gpu/drm/msm/msm_gem.c | 2 +-
drivers/gpu/drm/nouveau/nouveau_bo.c | 5 +-
drivers/gpu/drm/radeon/radeon_ttm.c | 9 ++-
drivers/gpu/drm/vgem/vgem_drv.c | 3 +-
drivers/gpu/drm/vkms/vkms_gem.c | 2 +-
drivers/gpu/drm/xen/xen_drm_front_gem.c | 4 +-
include/drm/drm_prime.h | 7 ++-
10 files changed, 69 insertions(+), 42 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index ac463e706b19..6a65490de391 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1011,8 +1011,8 @@ static int amdgpu_ttm_tt_pin_userptr(struct ttm_bo_device *bdev,
goto release_sg;
/* convert SG to linear array of pages and dma addresses */
- drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL, gtt->ttm.dma_address,
- ttm->num_pages);
+ drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
+ ttm->num_pages);
return 0;
@@ -1345,9 +1345,8 @@ static int amdgpu_ttm_tt_populate(struct ttm_bo_device *bdev,
ttm->sg = sgt;
}
- drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL,
- gtt->ttm.dma_address,
- ttm->num_pages);
+ drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
+ ttm->num_pages);
ttm_tt_set_populated(ttm);
return 0;
}
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 4910c446db83..8b750c074494 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -954,27 +954,25 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
EXPORT_SYMBOL(drm_gem_prime_import);
/**
- * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
+ * drm_prime_sg_to_page_array - 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
- * @addrs: optional array to store the dma bus address of each page
- * @max_entries: size of both the passed-in arrays
+ * @pages: array of page pointers to store the pages in
+ * @max_entries: size of the passed-in array
*
- * Exports an sg table into an array of pages and addresses. This is currently
- * required by the TTM driver in order to do correct fault handling.
+ * Exports an sg table into an array of pages.
*
- * Drivers can use this in their &drm_driver.gem_prime_import_sg_table
- * implementation.
+ * This function is deprecated and strongly discouraged to be used.
+ * The page 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)
+int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
+ struct page **pages,
+ int max_entries)
{
unsigned count;
struct scatterlist *sg;
struct page *page;
u32 page_len, page_index;
- dma_addr_t addr;
- u32 dma_len, dma_index;
/*
* Scatterlist elements contains both pages and DMA addresses, but
@@ -984,14 +982,11 @@ int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
* described by the sg_dma_address(sg).
*/
page_index = 0;
- dma_index = 0;
for_each_sg(sgt->sgl, sg, sgt->nents, count) {
page_len = sg->length;
page = sg_page(sg);
- dma_len = sg_dma_len(sg);
- addr = sg_dma_address(sg);
- while (pages && page_len > 0) {
+ while (page_len > 0) {
if (WARN_ON(page_index >= max_entries))
return -1;
pages[page_index] = page;
@@ -999,7 +994,43 @@ int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
page_len -= PAGE_SIZE;
page_index++;
}
- while (addrs && dma_len > 0) {
+ }
+ return 0;
+}
+EXPORT_SYMBOL(drm_prime_sg_to_page_array);
+
+/**
+ * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
+ * @sgt: scatter-gather table to convert
+ * @addrs: array to store the dma bus address of each page
+ * @max_entries: size of both the passed-in arrays
+ *
+ * Exports an sg table into an array of addresses.
+ *
+ * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
+ * implementation.
+ */
+int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
+ int max_entries)
+{
+ struct scatterlist *sg;
+ u32 dma_len, dma_index;
+ dma_addr_t addr;
+ unsigned count;
+
+ /*
+ * Scatterlist elements contains both pages and DMA addresses, but
+ * one shoud not assume 1:1 relation between them. The sg->length is
+ * the size of the physical memory chunk described by the sg->page,
+ * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk
+ * described by the sg_dma_address(sg).
+ */
+ dma_index = 0;
+ for_each_sg(sgt->sgl, sg, sgt->nents, count) {
+ dma_len = sg_dma_len(sg);
+ addr = sg_dma_address(sg);
+
+ while (dma_len > 0) {
if (WARN_ON(dma_index >= max_entries))
return -1;
addrs[dma_index] = addr;
@@ -1010,7 +1041,7 @@ int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
}
return 0;
}
-EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
+EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
/**
* drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
index 135fbff6fecf..8c04b8e8054c 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c
@@ -133,8 +133,7 @@ struct drm_gem_object *etnaviv_gem_prime_import_sg_table(struct drm_device *dev,
goto fail;
}
- ret = drm_prime_sg_to_page_addr_arrays(sgt, etnaviv_obj->pages,
- NULL, npages);
+ ret = drm_prime_sg_to_page_array(sgt, etnaviv_obj->pages, npages);
if (ret)
goto fail;
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index a71f42870d5e..616b87641740 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -1174,7 +1174,7 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,
goto fail;
}
- ret = drm_prime_sg_to_page_addr_arrays(sgt, msm_obj->pages, NULL, npages);
+ ret = drm_prime_sg_to_page_array(sgt, msm_obj->pages, npages);
if (ret) {
mutex_unlock(&msm_obj->lock);
goto fail;
diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index e378bb491688..835edd74ef59 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -1299,9 +1299,8 @@ nouveau_ttm_tt_populate(struct ttm_bo_device *bdev,
return 0;
if (slave && ttm->sg) {
- drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL,
- ttm_dma->dma_address,
- ttm->num_pages);
+ drm_prime_sg_to_dma_addr_array(ttm->sg, ttm_dma->dma_address,
+ ttm->num_pages);
ttm_tt_set_populated(ttm);
return 0;
}
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index 4b92cdbcd29b..7997e4564576 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -474,8 +474,8 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_bo_device *bdev, struct ttm_tt *
if (r)
goto release_sg;
- drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL, gtt->ttm.dma_address,
- ttm->num_pages);
+ drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
+ ttm->num_pages);
return 0;
@@ -642,9 +642,8 @@ static int radeon_ttm_tt_populate(struct ttm_bo_device *bdev,
}
if (slave && ttm->sg) {
- drm_prime_sg_to_page_addr_arrays(ttm->sg, NULL,
- gtt->ttm.dma_address,
- ttm->num_pages);
+ drm_prime_sg_to_dma_addr_array(ttm->sg, gtt->ttm.dma_address,
+ ttm->num_pages);
ttm_tt_set_populated(ttm);
return 0;
}
diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index ea0eecae5153..e505e5a291b3 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -356,8 +356,7 @@ static struct drm_gem_object *vgem_prime_import_sg_table(struct drm_device *dev,
}
obj->pages_pin_count++; /* perma-pinned */
- drm_prime_sg_to_page_addr_arrays(obj->table, obj->pages, NULL,
- npages);
+ drm_prime_sg_to_page_array(obj->table, obj->pages, npages);
return &obj->base;
}
diff --git a/drivers/gpu/drm/vkms/vkms_gem.c b/drivers/gpu/drm/vkms/vkms_gem.c
index 19a0e260a4df..a2ff21f47101 100644
--- a/drivers/gpu/drm/vkms/vkms_gem.c
+++ b/drivers/gpu/drm/vkms/vkms_gem.c
@@ -256,6 +256,6 @@ vkms_prime_import_sg_table(struct drm_device *dev,
return ERR_PTR(-ENOMEM);
}
- drm_prime_sg_to_page_addr_arrays(sg, obj->pages, NULL, npages);
+ drm_prime_sg_to_page_array(sg, obj->pages, npages);
return &obj->gem;
}
diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c b/drivers/gpu/drm/xen/xen_drm_front_gem.c
index f3830a0d1808..f4150ddfc5e2 100644
--- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
+++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
@@ -220,8 +220,8 @@ xen_drm_front_gem_import_sg_table(struct drm_device *dev,
xen_obj->sgt_imported = sgt;
- ret = drm_prime_sg_to_page_addr_arrays(sgt, xen_obj->pages,
- NULL, xen_obj->num_pages);
+ ret = drm_prime_sg_to_page_array(sgt, xen_obj->pages,
+ xen_obj->num_pages);
if (ret < 0)
return ERR_PTR(ret);
diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h
index 093f760cc131..4bda9ab3a3bb 100644
--- a/include/drm/drm_prime.h
+++ b/include/drm/drm_prime.h
@@ -103,8 +103,9 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg);
-int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
- dma_addr_t *addrs, int max_pages);
-
+int drm_prime_sg_to_page_array(struct sg_table *sgt, struct page **pages,
+ int max_pages);
+int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
+ int max_pages);
#endif /* __DRM_PRIME_H__ */
--
2.17.1