[PATCH v3 1/3] drm: add prime helpers
Daniel Vetter
daniel at ffwll.ch
Wed Jan 16 01:50:14 PST 2013
On Tue, Jan 15, 2013 at 12:47:42PM -0800, Aaron Plattner wrote:
> Instead of reimplementing all of the dma_buf functionality in every driver,
> create helpers drm_prime_import and drm_prime_export that implement them in
> terms of new, lower-level hook functions:
>
> gem_prime_pin: callback when a buffer is created, used to pin buffers into GTT
> gem_prime_get_sg_table: convert a drm_gem_object to an sg_table for export
> gem_prime_import_sg_table: convert an sg_table into a drm_gem_object
> gem_prime_vmap, gem_prime_vunmap: map and unmap an object
>
> These hooks are optional; drivers can opt in by using drm_gem_prime_import and
> drm_gem_prime_export as the .gem_prime_import and .gem_prime_export fields of
> struct drm_driver.
>
> v2:
> - Drop .begin_cpu_access. None of the drivers this code replaces implemented
> it. Having it here was a leftover from when I was trying to include i915 in
> this rework.
> - Use mutex_lock instead of mutex_lock_interruptible, as these three drivers
> did. This patch series shouldn't change that behavior.
> - Rename helpers to gem_prime_get_sg_table and gem_prime_import_sg_table.
> Rename struct sg_table* variables to 'sgt' for clarity.
> - Update drm.tmpl for these new hooks.
>
> v3:
> - Pass the vaddr down to the driver. This lets drivers that just call vunmap on
> the pointer avoid having to store the pointer in their GEM private structures.
> - Move documentation into a /** DOC */ comment in drm_prime.c and include it in
> drm.tmpl with a !P line. I tried to use !F lines to include documentation of
> the individual functions from drmP.h, but the docproc / kernel-doc scripts
> barf on that file, so hopefully this is good enough for now.
> - apply refcount fix from commit be8a42ae60addd8b6092535c11b42d099d6470ec
> ("drm/prime: drop reference on imported dma-buf come from gem")
>
> Signed-off-by: Aaron Plattner <aplattner at nvidia.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: David Airlie <airlied at linux.ie>
Two minor things, but since you're not touching drm/i915 I don't care that
much ...
> +static struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
> + enum dma_data_direction dir)
> +{
> + struct drm_gem_object *obj = attach->dmabuf->priv;
> + struct sg_table *sgt;
> +
> + mutex_lock(&obj->dev->struct_mutex);
> +
> + sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
> +
> + if (!IS_ERR_OR_NULL(sgt))
> + dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir);
> +
> + mutex_unlock(&obj->dev->struct_mutex);
The locking here looks superflous and not required to protect anything
drm_gem_map_dma_buf does. If drivers need this (and ttm based ones
shouldn't really), they can grab it in their ->gem_prime_get_sg_table
callback. So I think a follow-up patch to ditch this would be good.
> + return sgt;
> +}
> +
> +static void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
> + struct sg_table *sgt, enum dma_data_direction dir)
> +{
> + dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
> + sg_free_table(sgt);
> + kfree(sgt);
> +}
> +
> +static void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
> +{
> + struct drm_gem_object *obj = dma_buf->priv;
> +
> + if (obj->export_dma_buf == dma_buf) {
> + /* drop the reference on the export fd holds */
> + obj->export_dma_buf = NULL;
> + drm_gem_object_unreference_unlocked(obj);
> + }
> +}
> +
> +static void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
> +{
> + struct drm_gem_object *obj = dma_buf->priv;
> + struct drm_device *dev = obj->dev;
> +
> + return dev->driver->gem_prime_vmap(obj);
> +}
> +
> +static void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
> +{
> + struct drm_gem_object *obj = dma_buf->priv;
> + struct drm_device *dev = obj->dev;
> +
> + dev->driver->gem_prime_vunmap(obj, vaddr);
> +}
Imo these two don't add value, simpler to add a typechecking
drm_dmabuf_to_gem_obj static inline somewhere. But then you'd need to pass
in the dmabuf fops struct from drivers and export the helpers. More
flexible, but also a bit work to redo. Like I've said, I don't care too
much ...
-Daniel
> +
> +static void *drm_gem_dmabuf_kmap_atomic(struct dma_buf *dma_buf,
> + unsigned long page_num)
> +{
> + return NULL;
> +}
> +
> +static void drm_gem_dmabuf_kunmap_atomic(struct dma_buf *dma_buf,
> + unsigned long page_num, void *addr)
> +{
> +
> +}
> +static void *drm_gem_dmabuf_kmap(struct dma_buf *dma_buf,
> + unsigned long page_num)
> +{
> + return NULL;
> +}
> +
> +static void drm_gem_dmabuf_kunmap(struct dma_buf *dma_buf,
> + unsigned long page_num, void *addr)
> +{
> +
> +}
> +
> +static int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf,
> + struct vm_area_struct *vma)
> +{
> + return -EINVAL;
> +}
> +
> +static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = {
> + .map_dma_buf = drm_gem_map_dma_buf,
> + .unmap_dma_buf = drm_gem_unmap_dma_buf,
> + .release = drm_gem_dmabuf_release,
> + .kmap = drm_gem_dmabuf_kmap,
> + .kmap_atomic = drm_gem_dmabuf_kmap_atomic,
> + .kunmap = drm_gem_dmabuf_kunmap,
> + .kunmap_atomic = drm_gem_dmabuf_kunmap_atomic,
> + .mmap = drm_gem_dmabuf_mmap,
> + .vmap = drm_gem_dmabuf_vmap,
> + .vunmap = drm_gem_dmabuf_vunmap,
> +};
> +
> +/**
> + * DOC: PRIME Helpers
> + *
> + * Drivers can implement @gem_prime_export and @gem_prime_import in terms of
> + * simpler APIs by using the helper functions @drm_gem_prime_export and
> + * @drm_gem_prime_import. These functions implement dma-buf support in terms of
> + * five lower-level driver callbacks:
> + *
> + * Export callbacks:
> + *
> + * - @gem_prime_pin (optional): prepare a GEM object for exporting
> + *
> + * - @gem_prime_get_sg_table: provide a scatter/gather table of pinned pages
> + *
> + * - @gem_prime_vmap: vmap a buffer exported by your driver
> + *
> + * - @gem_prime_vunmap: vunmap a buffer exported by your driver
> + *
> + * Import callback:
> + *
> + * - @gem_prime_import_sg_table (import): produce a GEM object from another
> + * driver's scatter/gather table
> + */
> +
> +struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
> + struct drm_gem_object *obj, int flags)
> +{
> + if (dev->driver->gem_prime_pin) {
> + int ret = dev->driver->gem_prime_pin(obj);
> + if (ret)
> + return ERR_PTR(ret);
> + }
> + return dma_buf_export(obj, &drm_gem_prime_dmabuf_ops, obj->size,
> + 0600);
> +}
> +EXPORT_SYMBOL(drm_gem_prime_export);
> +
> int drm_gem_prime_handle_to_fd(struct drm_device *dev,
> struct drm_file *file_priv, uint32_t handle, uint32_t flags,
> int *prime_fd)
> @@ -117,6 +249,58 @@ int drm_gem_prime_handle_to_fd(struct drm_device *dev,
> }
> EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
>
> +struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
> + struct dma_buf *dma_buf)
> +{
> + struct dma_buf_attachment *attach;
> + struct sg_table *sgt;
> + struct drm_gem_object *obj;
> + int ret;
> +
> + if (!dev->driver->gem_prime_import_sg_table)
> + return ERR_PTR(-EINVAL);
> +
> + if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
> + obj = dma_buf->priv;
> + if (obj->dev == dev) {
> + /*
> + * 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;
> + }
> + }
> +
> + attach = dma_buf_attach(dma_buf, dev->dev);
> + if (IS_ERR(attach))
> + return ERR_PTR(PTR_ERR(attach));
> +
> + sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
> + if (IS_ERR_OR_NULL(sgt)) {
> + ret = PTR_ERR(sgt);
> + goto fail_detach;
> + }
> +
> + obj = dev->driver->gem_prime_import_sg_table(dev, dma_buf->size, sgt);
> + if (IS_ERR(obj)) {
> + ret = PTR_ERR(obj);
> + goto fail_unmap;
> + }
> +
> + obj->import_attach = attach;
> +
> + return obj;
> +
> +fail_unmap:
> + dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
> +fail_detach:
> + dma_buf_detach(dma_buf, attach);
> + return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL(drm_gem_prime_import);
> +
> int drm_gem_prime_fd_to_handle(struct drm_device *dev,
> struct drm_file *file_priv, int prime_fd, uint32_t *handle)
> {
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index fad21c9..2d4ca6f 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -919,6 +919,14 @@ struct drm_driver {
> /* import dmabuf -> GEM */
> struct drm_gem_object * (*gem_prime_import)(struct drm_device *dev,
> struct dma_buf *dma_buf);
> + /* low-level interface used by drm_gem_prime_{import,export} */
> + int (*gem_prime_pin)(struct drm_gem_object *obj);
> + struct sg_table *(*gem_prime_get_sg_table)(struct drm_gem_object *obj);
> + struct drm_gem_object *(*gem_prime_import_sg_table)(
> + struct drm_device *dev, size_t size,
> + struct sg_table *sgt);
> + void *(*gem_prime_vmap)(struct drm_gem_object *obj);
> + void (*gem_prime_vunmap)(struct drm_gem_object *obj, void *vaddr);
>
> /* vga arb irq handler */
> void (*vgaarb_irq)(struct drm_device *dev, bool state);
> @@ -1540,9 +1548,13 @@ extern int drm_clients_info(struct seq_file *m, void* data);
> extern int drm_gem_name_info(struct seq_file *m, void *data);
>
>
> +extern struct dma_buf *drm_gem_prime_export(struct drm_device *dev,
> + struct drm_gem_object *obj, int flags);
> extern int drm_gem_prime_handle_to_fd(struct drm_device *dev,
> struct drm_file *file_priv, uint32_t handle, uint32_t flags,
> int *prime_fd);
> +extern struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
> + struct dma_buf *dma_buf);
> extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
> struct drm_file *file_priv, int prime_fd, uint32_t *handle);
>
> --
> 1.8.1.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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