[PATCHv2 1/1] staging/ion: Add support to get ion handle from dma buf

Sumit Semwal sumit.semwal at linaro.org
Thu Jan 7 14:13:09 UTC 2016


Hi Rohit,

On 6 January 2016 at 12:41, Rohit kumar <rohit.kr at samsung.com> wrote:
> Currently we can only import dma buf fd's to get ion_handle.
> Adding support to import dma buf handles to support kernel
> specific use cases.
>
> An example use case is in linux platforms such as Tizen, in which
> DRM-GEM is used for buffer management for graphics. It has gem_handle
> corresponding to a buffer and uses gem_name for sharing the buffer
> with other processes. However,it also uses dma_buf fd for 3d operations.
> For wayland, there are multiple calls for gem_handle to dma_buf fd
> conversion. So, we store dma_buf associated with buffer. But, there is
> no api for getting ion_handle from dma_buf. This patch exposes api to
> retrieve the ion handle from dma_buf for similar use cases. With this
> patch, we can integrate ION within DRM-GEM for buffer management and
> dma_buf sharing.
>
> Signed-off-by: Rohit kumar <rohit.kr at samsung.com>
> ---
> v2: Updated commit message with use case explanation, as suggested by
>     Laura Abbott<labbott at redhat.com>
>
Thanks for this patch.

In general it looks good to me, but perhaps you should add related ION
tests for this as well? Once you add that and share for review, feel
free to add
Reviewed-by: Sumit Semwal <sumit.semwal at linaro.org>

>  drivers/staging/android/ion/ion.c |   21 +++++++++++++++------
>  drivers/staging/android/ion/ion.h |   20 ++++++++++++++++----
>  2 files changed, 31 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index e237e9f..5509716 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -1151,16 +1151,13 @@ int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle)
>  }
>  EXPORT_SYMBOL(ion_share_dma_buf_fd);
>
> -struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd)
> +struct ion_handle *ion_import_dma_buf(struct ion_client *client,
> +                                     struct dma_buf *dmabuf)
>  {
> -       struct dma_buf *dmabuf;
>         struct ion_buffer *buffer;
>         struct ion_handle *handle;
>         int ret;
>
> -       dmabuf = dma_buf_get(fd);
> -       if (IS_ERR(dmabuf))
> -               return ERR_CAST(dmabuf);
>         /* if this memory came from ion */
>
>         if (dmabuf->ops != &dma_buf_ops) {
> @@ -1199,6 +1196,18 @@ end:
>  }
>  EXPORT_SYMBOL(ion_import_dma_buf);
>
> +struct ion_handle *ion_import_dma_buf_fd(struct ion_client *client, int fd)
> +{
> +       struct dma_buf *dmabuf;
> +
> +       dmabuf = dma_buf_get(fd);
> +       if (IS_ERR(dmabuf))
> +               return ERR_CAST(dmabuf);
> +
> +       return ion_import_dma_buf(client, dmabuf);
> +}
> +EXPORT_SYMBOL(ion_import_dma_buf_fd);
> +
>  static int ion_sync_for_device(struct ion_client *client, int fd)
>  {
>         struct dma_buf *dmabuf;
> @@ -1306,7 +1315,7 @@ static long ion_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>         {
>                 struct ion_handle *handle;
>
> -               handle = ion_import_dma_buf(client, data.fd.fd);
> +               handle = ion_import_dma_buf_fd(client, data.fd.fd);
>                 if (IS_ERR(handle))
>                         ret = PTR_ERR(handle);
>                 else
> diff --git a/drivers/staging/android/ion/ion.h b/drivers/staging/android/ion/ion.h
> index b860c5f..a1331fc 100644
> --- a/drivers/staging/android/ion/ion.h
> +++ b/drivers/staging/android/ion/ion.h
> @@ -192,14 +192,26 @@ struct dma_buf *ion_share_dma_buf(struct ion_client *client,
>  int ion_share_dma_buf_fd(struct ion_client *client, struct ion_handle *handle);
>
>  /**
> - * ion_import_dma_buf() - given an dma-buf fd from the ion exporter get handle
> + * ion_import_dma_buf() - get ion_handle from dma-buf
> + * @client:    the client
> + * @dmabuf:    the dma-buf
> + *
> + * Get the ion_buffer associated with the dma-buf and return the ion_handle.
> + * If no ion_handle exists for this buffer, return newly created ion_handle.
> + * If dma-buf from another exporter is passed, return ERR_PTR(-EINVAL)
> + */
> +struct ion_handle *ion_import_dma_buf(struct ion_client *client,
> +                                     struct dma_buf *dmabuf);
> +
> +/**
> + * ion_import_dma_buf_fd() - given a dma-buf fd from the ion exporter get handle
>   * @client:    the client
>   * @fd:                the dma-buf fd
>   *
> - * Given an dma-buf fd that was allocated through ion via ion_share_dma_buf,
> - * import that fd and return a handle representing it.  If a dma-buf from
> + * Given an dma-buf fd that was allocated through ion via ion_share_dma_buf_fd,
> + * import that fd and return a handle representing it. If a dma-buf from
>   * another exporter is passed in this function will return ERR_PTR(-EINVAL)
>   */
> -struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd);
> +struct ion_handle *ion_import_dma_buf_fd(struct ion_client *client, int fd);
>
>  #endif /* _LINUX_ION_H */
> --
> 1.7.9.5
>



-- 
Thanks and regards,

Sumit Semwal
Linaro Mobile Group - Kernel Team Lead
Linaro.org │ Open source software for ARM SoCs


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