Hi Laurent, a few mostly-minor comments, although from a quick look the sg_alloc_table()/sg_free_table() doesn't look quite right in all cases. The other comments could just be a subject for a later patch if it is something that somebody needs some day..

On Mon, Apr 15, 2013 at 9:57 AM, Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com wrote:

Signed-off-by: Laurent Pinchart laurent.pinchart+renesas@ideasonboard.com

drivers/gpu/drm/drm_gem_cma_helper.c | 311 ++++++++++++++++++++++++++++++++++- include/drm/drm_gem_cma_helper.h | 9 + 2 files changed, 317 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index 8cce330..c428a51 100644 --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -21,6 +21,9 @@ #include <linux/slab.h> #include <linux/mutex.h> #include <linux/export.h> +#if CONFIG_DMA_SHARED_BUFFER +#include <linux/dma-buf.h> +#endif #include <linux/dma-mapping.h>

#include <drm/drmP.h> @@ -82,6 +85,8 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, unsigned int size) { struct drm_gem_cma_object *cma_obj;

•   struct sg_table *sgt = NULL;
  

•   int ret;
  
    size = round_up(size, PAGE_SIZE);
  
  

@@ -94,11 +99,29 @@ struct drm_gem_cma_object *drm_gem_cma_create(struct drm_device *drm, if (!cma_obj->vaddr) { dev_err(drm->dev, "failed to allocate buffer with size %d\n", size);

•           drm_gem_cma_free_object(&cma_obj->base);
  

•           return ERR_PTR(-ENOMEM);
  

•           ret = -ENOMEM;
  

•           goto error;
    }
  
  

•   sgt = kzalloc(sizeof(*cma_obj->sgt), GFP_KERNEL);
  

•   if (sgt == NULL) {
  

•           ret = -ENOMEM;
  

•           goto error;
  

•   }
  

•   ret = dma_get_sgtable(drm->dev, sgt, cma_obj->vaddr,
  

•                         cma_obj->paddr, size);
  

•   if (ret < 0)
  

•           goto error;
  

•   cma_obj->sgt = sgt;
  

•   return cma_obj;
  

+error:

•   kfree(sgt);
  

•   drm_gem_cma_free_object(&cma_obj->base);
  

•   return ERR_PTR(ret);
  

} EXPORT_SYMBOL_GPL(drm_gem_cma_create);

@@ -156,9 +179,16 @@ void drm_gem_cma_free_object(struct drm_gem_object *gem_obj)

    cma_obj = to_drm_gem_cma_obj(gem_obj);

•   if (cma_obj->vaddr)
  

•   if (cma_obj->vaddr) {
            dma_free_writecombine(gem_obj->dev->dev, cma_obj->base.size,
                                  cma_obj->vaddr, cma_obj->paddr);
  

•           if (cma_obj->sgt) {
  

•                   sg_free_table(cma_obj->sgt);
  

•                   kfree(cma_obj->sgt);
  

•           }
  

•   } else if (gem_obj->import_attach) {
  

•           drm_prime_gem_destroy(gem_obj, cma_obj->sgt);
  

•   }
  
    drm_gem_object_release(gem_obj);
  
  

@@ -282,4 +312,279 @@ void drm_gem_cma_describe(struct drm_gem_cma_object *cma_obj, struct seq_file *m seq_printf(m, "\n"); } EXPORT_SYMBOL_GPL(drm_gem_cma_describe);

+/* -----------------------------------------------------------------------------

• • DMA-BUF
• */

+#if CONFIG_DMA_SHARED_BUFFER +struct drm_gem_cma_dmabuf_attachment {

•   struct sg_table sgt;
  

•   enum dma_data_direction dir;
  

+};

+static int drm_gem_cma_dmabuf_attach(struct dma_buf *dmabuf, struct device *dev,

•                                struct dma_buf_attachment *attach)
  

+{

•   struct drm_gem_cma_dmabuf_attachment *cma_attach;
  

•   cma_attach = kzalloc(sizeof(*cma_attach), GFP_KERNEL);
  

•   if (!cma_attach)
  

•           return -ENOMEM;
  

•   cma_attach->dir = DMA_NONE;
  

•   attach->priv = cma_attach;
  

•   return 0;
  

+}

+static void drm_gem_cma_dmabuf_detach(struct dma_buf *dmabuf,

•                                 struct dma_buf_attachment *attach)
  

+{

•   struct drm_gem_cma_dmabuf_attachment *cma_attach = attach->priv;
  

•   struct sg_table *sgt;
  

•   if (cma_attach == NULL)
  

•           return;
  

•   sgt = &cma_attach->sgt;
  

•   if (cma_attach->dir != DMA_NONE)
  

•           dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents,
  

•                           cma_attach->dir);
  

•   sg_free_table(sgt);
  

•   kfree(cma_attach);
  

•   attach->priv = NULL;
  

+}

+static struct sg_table * +drm_gem_cma_dmabuf_map(struct dma_buf_attachment *attach,

•                  enum dma_data_direction dir)
  

+{

•   struct drm_gem_cma_dmabuf_attachment *cma_attach = attach->priv;
  

•   struct drm_gem_cma_object *cma_obj = attach->dmabuf->priv;
  

•   struct drm_device *drm = cma_obj->base.dev;
  

•   struct scatterlist *rd, *wr;
  

•   struct sg_table *sgt;
  

•   unsigned int i;
  

•   int nents, ret;
  

•   DRM_DEBUG_PRIME("\n");
  

•   if (WARN_ON(dir == DMA_NONE))
  

•           return ERR_PTR(-EINVAL);
  

•   /* Return the cached mapping when possible. */
  

•   if (cma_attach->dir == dir)
  

•           return &cma_attach->sgt;
  

•   /* Two mappings with different directions for the same attachment are
  

•    * not allowed.
  

•    */
  

•   if (WARN_ON(cma_attach->dir != DMA_NONE))
  

•           return ERR_PTR(-EBUSY);
  

•   sgt = &cma_attach->sgt;
  

•   ret = sg_alloc_table(sgt, cma_obj->sgt->orig_nents, GFP_KERNEL);
  

•   if (ret) {
  

•           DRM_ERROR("failed to alloc sgt.\n");
  

•           return ERR_PTR(-ENOMEM);
  

•   }
  

•   mutex_lock(&drm->struct_mutex);
  

•   rd = cma_obj->sgt->sgl;
  

•   wr = sgt->sgl;
  

•   for (i = 0; i < sgt->orig_nents; ++i) {
  

•           sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
  

•           rd = sg_next(rd);
  

•           wr = sg_next(wr);
  

•   }
  

•   nents = dma_map_sg(attach->dev, sgt->sgl, sgt->orig_nents, dir);
  

•   if (!nents) {
  

•           DRM_ERROR("failed to map sgl with iommu.\n");
  

•           sgt = ERR_PTR(-EIO);
  

•           goto err_unlock;
  

don't we miss a sg_free_table() in this error path? Or, well, I guess you still call it in _detach(), but if you call _map() again, I think we'll re-sg_alloc_table(), which doesn't seem quite right..

•   }
  

•   cma_attach->dir = dir;
  

•   attach->priv = cma_attach;
  

•   DRM_DEBUG_PRIME("buffer size = %zu\n", cma_obj->base.size);
  

+err_unlock:

•   mutex_unlock(&drm->struct_mutex);
  

•   return sgt;
  

+}

+static void drm_gem_cma_dmabuf_unmap(struct dma_buf_attachment *attach,

•                                struct sg_table *sgt,
  

•                                enum dma_data_direction dir)
  

+{

•   /* Nothing to do. */
  

hmm, I wonder if it makes sense to support _unmap() and then _map() again with a different direction? Not entirely sure when that would be needed and I suppose it is ok to add later.

+}

+static void drm_gem_cma_dmabuf_release(struct dma_buf *dmabuf) +{

•   struct drm_gem_cma_object *cma_obj = dmabuf->priv;
  

•   DRM_DEBUG_PRIME("%s\n", __FILE__);
  

•   /*
  

•    * drm_gem_cma_dmabuf_release() call means that file object's
  

•    * f_count is 0 and it calls drm_gem_object_handle_unreference()
  

•    * to drop the references that these values had been increased
  

•    * at drm_prime_handle_to_fd()
  

•    */
  

•   if (cma_obj->base.export_dma_buf == dmabuf) {
  

•           cma_obj->base.export_dma_buf = NULL;
  

•           /*
  

•            * drop this gem object refcount to release allocated buffer
  

•            * and resources.
  

•            */
  

•           drm_gem_object_unreference_unlocked(&cma_obj->base);
  

•   }
  

+}

+static void *drm_gem_cma_dmabuf_kmap_atomic(struct dma_buf *dmabuf,

•                                       unsigned long page_num)
  

+{

•   /* TODO */
  

•   return NULL;
  

+}

+static void drm_gem_cma_dmabuf_kunmap_atomic(struct dma_buf *dmabuf,

•                                        unsigned long page_num, void *addr)
  

+{

•   /* TODO */
  

+}

+static void *drm_gem_cma_dmabuf_kmap(struct dma_buf *dmabuf,

•                                unsigned long page_num)
  

+{

•   /* TODO */
  

•   return NULL;
  

+}

+static void drm_gem_cma_dmabuf_kunmap(struct dma_buf *dmabuf,

•                                 unsigned long page_num, void *addr)
  

+{

•   /* TODO */
  

+}

again, not really sure if it is required, but it should be pretty trivial to support kmap and friends

+static int drm_gem_cma_dmabuf_mmap(struct dma_buf *dmabuf,

•                              struct vm_area_struct *vma)
  

+{

•   return -ENOTTY;
  

+}

should also be pretty trivial to redirect _dmabuf_mmap() into drm_gem_cma_mmap()..

+static void *drm_gem_cma_dmabuf_vmap(struct dma_buf *dmabuf) +{

•   struct drm_gem_cma_object *cma_obj = dmabuf->priv;
  

•   return cma_obj->vaddr;
  

+}

+static struct dma_buf_ops drm_gem_cma_dmabuf_ops = {

•   .attach                 = drm_gem_cma_dmabuf_attach,
  

•   .detach                 = drm_gem_cma_dmabuf_detach,
  

•   .map_dma_buf            = drm_gem_cma_dmabuf_map,
  

•   .unmap_dma_buf          = drm_gem_cma_dmabuf_unmap,
  

•   .kmap                   = drm_gem_cma_dmabuf_kmap,
  

•   .kmap_atomic            = drm_gem_cma_dmabuf_kmap_atomic,
  

•   .kunmap                 = drm_gem_cma_dmabuf_kunmap,
  

•   .kunmap_atomic          = drm_gem_cma_dmabuf_kunmap_atomic,
  

•   .mmap                   = drm_gem_cma_dmabuf_mmap,
  

•   .vmap                   = drm_gem_cma_dmabuf_vmap,
  

•   .release                = drm_gem_cma_dmabuf_release,
  

+};

+struct dma_buf *drm_gem_cma_dmabuf_export(struct drm_device *drm,

•                                     struct drm_gem_object *obj, int flags)
  

+{

•   struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
  

•   return dma_buf_export(cma_obj, &drm_gem_cma_dmabuf_ops,
  

•                         cma_obj->base.size, flags);
  

+} +EXPORT_SYMBOL_GPL(drm_gem_cma_dmabuf_export);

+struct drm_gem_object *drm_gem_cma_dmabuf_import(struct drm_device *drm,

•                                            struct dma_buf *dma_buf)
  

+{

•   struct drm_gem_cma_object *cma_obj;
  

•   struct dma_buf_attachment *attach;
  

•   struct sg_table *sgt;
  

•   int ret;
  

•   DRM_DEBUG_PRIME("%s\n", __FILE__);
  

•   /* is this one of own objects? */
  

•   if (dma_buf->ops == &drm_gem_cma_dmabuf_ops) {
  

•           struct drm_gem_object *obj;
  

•           cma_obj = dma_buf->priv;
  

•           obj = &cma_obj->base;
  

•           /* is it from our device? */
  

•           if (obj->dev == drm) {
  

•                   /*
  

•                    * Importing dmabuf exported from out own gem increases
  

•                    * refcount on gem itself instead of f_count of dmabuf.
  

•                    */
  

•                   drm_gem_object_reference(obj);
  

•                   dma_buf_put(dma_buf);
  

•                   return obj;
  

•           }
  

•   }
  

•   /* Create a CMA GEM buffer. */
  

•   cma_obj = __drm_gem_cma_create(drm, dma_buf->size);
  

•   if (IS_ERR(cma_obj))
  

•           return ERR_PTR(PTR_ERR(cma_obj));
  

•   /* Attach to the buffer and map it. Make sure the mapping is contiguous
  

•    * on the device memory bus, as that's all we support.
  

•    */
  

•   attach = dma_buf_attach(dma_buf, drm->dev);
  

•   if (IS_ERR(attach)) {
  

•           ret = -EINVAL;
  

•           goto error_gem_free;
  

•   }
  

•   sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
  

•   if (IS_ERR_OR_NULL(sgt)) {
  

•           ret = sgt ? PTR_ERR(sgt) : -ENOMEM;
  

•           goto error_buf_detach;
  

•   }
  

•   if (sgt->nents != 1) {
  

•           ret = -EINVAL;
  

•           goto error_buf_unmap;
  

•   }
  

•   cma_obj->base.import_attach = attach;
  

•   cma_obj->paddr = sg_dma_address(sgt->sgl);
  

•   cma_obj->sgt = sgt;
  

•   DRM_DEBUG_PRIME("dma_addr = 0x%x, size = %zu\n", cma_obj->paddr,
  

•                   dma_buf->size);
  

•   return &cma_obj->base;
  

+error_buf_unmap:

•   dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
  

+error_buf_detach:

•   dma_buf_detach(dma_buf, attach);
  

+error_gem_free:

•   drm_gem_cma_free_object(&cma_obj->base);
  

•   return ERR_PTR(ret);
  

+} +EXPORT_SYMBOL_GPL(drm_gem_cma_dmabuf_import); #endif diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h index 63397ce..6e17251 100644 --- a/include/drm/drm_gem_cma_helper.h +++ b/include/drm/drm_gem_cma_helper.h @@ -4,6 +4,9 @@ struct drm_gem_cma_object { struct drm_gem_object base; dma_addr_t paddr;

•   struct sg_table *sgt;
  

•   /* For objects with DMA memory allocated by GEM CMA */
    void *vaddr;
  

};

@@ -45,4 +48,10 @@ extern const struct vm_operations_struct drm_gem_cma_vm_ops; void drm_gem_cma_describe(struct drm_gem_cma_object *obj, struct seq_file *m); #endif

+struct dma_buf *drm_gem_cma_dmabuf_export(struct drm_device *drm_dev,

•                                     struct drm_gem_object *obj,
  

•                                     int flags);
  

+struct drm_gem_object *drm_gem_cma_dmabuf_import(struct drm_device *drm_dev,

•                                            struct dma_buf *dma_buf);
  

#endif /* __DRM_GEM_CMA_HELPER_H__ */

1.8.1.5