Am 14.03.23 um 11:52 schrieb Paul Cercueil:
Hi,
This small patchset adds three new IOCTLs that can be used to attach,
detach, or transfer from/to a DMABUF object.
This was surprisingly easy to add, as the functionfs code only uses
scatterlists for transfers and allows specifying the number of bytes to
transfer. The bulk of the code is then for general DMABUF accounting.
The patchset isn't tagged RFC but comments are very welcome, there are
some things I am not 100% sure about: ffs_dma_resv_lock (with no
ww_acquire_ctx),
That is perfectly fine as long as you only want to lock one dma_resv object.
I've made a few notes what should be fixed and could potentially be
improved, but from the DMA-buf side that looks like it should mostly work.
Regards,
Christian.
and I'm using pr_debug which feels wrong. Also, I
should probably add documentation? The current IOCTLs for functionfs
were not documented, as far as I can tell.
We use it with DMABUFs created with udmabuf, that we attach to the
functionfs interface and to IIO devices (with a DMABUF interface for
IIO, on its way to upstream too), to transfer samples from high-speed
transceivers to USB in a zero-copy fashion.
Cheers,
-Paul
Paul Cercueil (2):
usb: gadget: Support already-mapped DMA SGs
usb: gadget: functionfs: Add DMABUF import interface
drivers/usb/gadget/function/f_fs.c | 398 ++++++++++++++++++++++++++++
drivers/usb/gadget/udc/core.c | 7 +-
include/linux/usb/gadget.h | 2 +
include/uapi/linux/usb/functionfs.h | 14 +-
4 files changed, 419 insertions(+), 2 deletions(-)
