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

[Rohit <rohit.kr@samsung.com>]

Hi Sumit,

On Thu, 07 Jan 2016 19:43:09 +0530
Sumit Semwal <sumit.semwal@linaro.org> wrote:

> Hi Rohit,
> 
> On 6 January 2016 at 12:41, Rohit kumar <rohit.kr@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@samsung.com>
> > ---
> > v2: Updated commit message with use case explanation, as suggested
> > by Laura Abbott<labbott@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
Thanks for the suggestion. I would add related ION test and share for
review sooner.
> Reviewed-by: Sumit Semwal <sumit.semwal@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
> >
> 
> 
>