Re: [Linaro-mm-sig] [PATCH 6/6] drm/prime: document that use the page array is deprecated v2

On Fri, Oct 9, 2020 at 6:24 PM Daniel Vetter daniel@ffwll.ch wrote:

On Fri, Oct 09, 2020 at 05:03:42PM +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.

v2: split it into two functions

Signed-off-by: Christian König christian.koenig@amd.com

Patches 3-5:

Acked-by: Daniel Vetter daniel.vetter@ffwll.ch

This one looks good, but you have it on a strange baseline. This doesn't contain the sg walking fixes from Marek, so reintroduces the bugs. Probably need to request a backmerge chain, first of -rc8 into drm-next, and then that into drm-misc-next.

Marek's patch is in drm-next, so just needs a backmerge into drm-misc-next.

Thomas, can you pls do that? We need 0552daac2d18f

I'll wait for the next round for patches 1&2 since Jason seems to have found a small issue with them. -Daniel

Everything else in here lgtm. -Daniel

...

---

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

s/should/can/

There's no requirement, if your driver just handles everything as an sgt there's no conversion needed.

...

• • 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

-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch