Commit 89177644 authored by Aaron Plattner's avatar Aaron Plattner Committed by Dave Airlie
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drm: add prime helpers 



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 be8a42ae
  ("drm/prime: drop reference on imported dma-buf come from gem")

Signed-off-by: default avatarAaron Plattner <aplattner@nvidia.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 6504d0d9

Documentation/DocBook/drm.tmpl

+4 −0
Original line number Diff line number Diff line
@@ -743,6 +743,10 @@ char *date;</synopsis> 
          These two operations are mandatory for GEM drivers that support DRM

          PRIME.

        </para>

        <sect4>

          <title>DRM PRIME Helper Functions Reference</title>

!Pdrivers/gpu/drm/drm_prime.c PRIME Helpers

        </sect4>

      </sect3>

      <sect3 id="drm-gem-objects-mapping">

        <title>GEM Objects Mapping</title>

drivers/gpu/drm/drm_prime.c

+185 −1
Original line number Diff line number Diff line
@@ -53,7 +53,8 @@ 
 * Self-importing: if userspace is using PRIME as a replacement for flink

 * then it will get a fd->handle request for a GEM object that it created.

 * Drivers should detect this situation and return back the gem object

 * from the dma-buf private.

 * from the dma-buf private.  Prime will do this automatically for drivers that

 * use the drm_gem_prime_{import,export} helpers.

 */



struct drm_prime_member {
@@ -62,6 +63,137 @@ struct drm_prime_member { 
	uint32_t handle;

};



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);

	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);

}



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)

{

include/drm/drmP.h

+12 −0
Original line number Diff line number Diff line
@@ -930,6 +930,14 @@ 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);
@@ -1562,9 +1570,13 @@ 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);

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