On Sat, 2024-06-15 at 13:07 +0200, Paul Cercueil wrote: > Le dimanche 09 juin 2024 à 10:53 +0100, Jonathan Cameron a écrit : > > On Wed, 5 Jun 2024 13:08:42 +0200 > > Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote: > > > > > Add the necessary infrastructure to the IIO core to support a new > > > optional DMABUF based interface. > > > > > > With this new interface, DMABUF objects (externally created) can be > > > attached to a IIO buffer, and subsequently used for data transfer. > > > > > > A userspace application can then use this interface to share DMABUF > > > objects between several interfaces, allowing it to transfer data in > > > a > > > zero-copy fashion, for instance between IIO and the USB stack. > > > > > > The userspace application can also memory-map the DMABUF objects, > > > and > > > access the sample data directly. The advantage of doing this vs. > > > the > > > read() interface is that it avoids an extra copy of the data > > > between the > > > kernel and userspace. This is particularly userful for high-speed > > > devices which produce several megabytes or even gigabytes of data > > > per > > > second. > > > > > > As part of the interface, 3 new IOCTLs have been added: > > > > > > IIO_BUFFER_DMABUF_ATTACH_IOCTL(int fd): > > > Attach the DMABUF object identified by the given file descriptor > > > to the > > > buffer. > > > > > > IIO_BUFFER_DMABUF_DETACH_IOCTL(int fd): > > > Detach the DMABUF object identified by the given file descriptor > > > from > > > the buffer. Note that closing the IIO buffer's file descriptor > > > will > > > automatically detach all previously attached DMABUF objects. > > > > > > IIO_BUFFER_DMABUF_ENQUEUE_IOCTL(struct iio_dmabuf *): > > > Request a data transfer to/from the given DMABUF object. Its file > > > descriptor, as well as the transfer size and flags are provided in > > > the > > > "iio_dmabuf" structure. > > > > > > These three IOCTLs have to be performed on the IIO buffer's file > > > descriptor, obtained using the IIO_BUFFER_GET_FD_IOCTL() ioctl. > > > > > > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx> > > > Signed-off-by: Nuno Sa <nuno.sa@xxxxxxxxxx> > > > > Need a brief note on the sign off chain. > > What is Nuno's role in this series as he's not sending the emails and > > not > > marked with Co-developed-by > > That's a good question. I think he sent one revision of the patchset > (v7 or something like that) so he added his SoB. > > (Nuno: you confirm?) exactly... > > I'll add his Co-developed-by then. Not sure if that is really deserved :)... Maybe just remove my tag. - Nuno Sá
