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

[Rohit]

Sorry to resend the patch without [RESEND] tag. Actually I had missed
to add  devel at driverdev.osuosl.org, linux-kernel at vger.kernel.org in
mail last time.

I will update the commit message with the explanation and send the
PATCHv2 soon.

Thanks,
Rohit

On Tue, 05 Jan 2016 10:12:39 -0800
Laura Abbott <labbott at redhat.com> wrote:

> On 01/05/2016 05:03 AM, Rohit kumar 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.
> >
> > Signed-off-by: Rohit kumar <rohit.kr at samsung.com>
> > ---
> > Currently, ION is the memory manager for graphics in android.
> > However, in other linux platforms such as Tizen, 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.
> >
> 
> Is this the same patch that was sent on 12/29? In general it's best to
> wait a bit longer before resending, especially with lots of people
> being off for the holidays. Please also tag your patch with [RESEND]
> so it's easier to tell that this is the same patch being sent again.
> 
> This is also a good explanation that should be included in the commit
> text as well. It gives a much more thorough explanation why this
> API is needed. The substance of the patch looks okay to me.
> 
> Thanks,
> Laura
> 
> >   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 */
> >
> 
>