[Linaro-mm-sig] [PATCH 5/7] drm/vgem: prime export support

[Chris Wilson]

On Wed, 22 Feb 2012 20:29:18 +0100, Ben Widawsky <ben at bwidawsk.net> wrote:
> dma-buf export implementation. Heavily influenced by Dave Airlie's proof
> of concept work.
> 
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Dave Airlie <airlied at redhat.com>
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
>  drivers/gpu/drm/vgem/Makefile       |    2 +-
>  drivers/gpu/drm/vgem/vgem_dma_buf.c |  128 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/vgem/vgem_drv.c     |    6 ++
>  drivers/gpu/drm/vgem/vgem_drv.h     |    7 ++
>  4 files changed, 142 insertions(+), 1 deletions(-)
>  create mode 100644 drivers/gpu/drm/vgem/vgem_dma_buf.c
> 
> diff --git a/drivers/gpu/drm/vgem/Makefile b/drivers/gpu/drm/vgem/Makefile
> index 3f4c7b8..1055cb7 100644
> --- a/drivers/gpu/drm/vgem/Makefile
> +++ b/drivers/gpu/drm/vgem/Makefile
> @@ -1,4 +1,4 @@
>  ccflags-y := -Iinclude/drm
> -vgem-y := vgem_drv.o
> +vgem-y := vgem_drv.o vgem_dma_buf.o
>  
>  obj-$(CONFIG_DRM_VGEM)	+= vgem.o
> diff --git a/drivers/gpu/drm/vgem/vgem_dma_buf.c b/drivers/gpu/drm/vgem/vgem_dma_buf.c
> new file mode 100644
> index 0000000..eca9445
> --- /dev/null
> +++ b/drivers/gpu/drm/vgem/vgem_dma_buf.c
> @@ -0,0 +1,128 @@
> +/*
> + * Copyright © 2012 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + * Authors:
> + *    Ben Widawsky <ben at bwidawsk.net>
> + *
> + */
> +
> +#include <linux/dma-buf.h>
> +#include "vgem_drv.h"
> +
> +#define VGEM_FD_PERMS 0600
> +
> +struct sg_table *vgem_gem_map_dma_buf(struct dma_buf_attachment *attachment,
> +                                      enum dma_data_direction dir)
I guess I'm just not quite happy with the dma-buf interface, but I'd
have liked to have avoided the whole sg_table allocation and have made
the dma_buf embeddable. Daniel is slacking!

> +int vgem_prime_to_fd(struct drm_device *dev, struct drm_file *file,
> +		     uint32_t handle, int *prime_fd)
> +{
> +	struct drm_vgem_file_private *file_priv = file->driver_priv;
> +	struct drm_vgem_gem_object *obj;
> +	int ret;
> +
> +	DRM_DEBUG_PRIME("Request fd for handle %d\n", handle);
> +
> +	obj = to_vgem_bo(drm_gem_object_lookup(dev, file, handle));
> +	if (!obj)
> +		return -EBADF;
-ENOENT; EBADF is for reporting that ioctl was itself called on an invalid fd.

locking fail.

> +	/* This means a user has already called get_fd on this */
> +	if (obj->base.prime_fd != -1) {
> +		DRM_DEBUG_PRIME("User requested a previously exported buffer "
> +				"%d %d\n", handle, obj->base.prime_fd);
> +		drm_gem_object_unreference(&obj->base);
> +		goto out_fd;
> +	}
> +
> +	/* Make a dma buf out of our vgem object */
> +	obj->base.export_dma_buf = dma_buf_export(obj, &vgem_dmabuf_ops,
> +						  obj->base.size,
> +						  VGEM_FD_PERMS);
locking fail.

> +	if (IS_ERR(obj->base.export_dma_buf)) {
> +		DRM_DEBUG_PRIME("export fail\n");
> +		return PTR_ERR(obj->base.export_dma_buf);
> +	} else
> +		obj->base.prime_fd = dma_buf_fd(obj->base.export_dma_buf);
locking fail... ;-)

> +
> +	mutex_lock(&dev->prime_mutex);
Per-device mutex for a per-file hash-table?

> +	ret = drm_prime_insert_fd_handle_mapping(&file_priv->prime,
> +						 obj->base.export_dma_buf,
> +						 handle);
> +	WARN_ON(ret);
> +	ret = drm_prime_add_dma_buf(dev, &obj->base);
> +	mutex_unlock(&dev->prime_mutex);
> +	if (ret)
> +		return ret;
> +
> +out_fd:
> +	*prime_fd = obj->base.prime_fd;
> +
> +	return 0;
> +}
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre