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@xxxxxxxxxxxxxxxx> wrote:
> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> ---
> 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
>
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