Hi Andrzej,
Le vendredi 31 mars 2023 à 11:40 +0200, Andrzej Pietrasiewicz a écrit :
Hi Paul,
W dniu 22.03.2023 o 10:21, Paul Cercueil pisze:
Hi,
This small patchset adds three new IOCTLs that can be used to attach, detach, or transfer from/to a DMABUF object.
Changes since v1:
- patch [2/3] is new. I had to reuse a piece of code that was
already duplicated in the driver, so I factorized the code.
- Make ffs_dma_resv_lock() static
- Add MODULE_IMPORT_NS(DMA_BUF);
- The attach/detach functions are now performed without locking the
eps_lock spinlock. The transfer function starts with the spinlock unlocked, then locks it before allocating and queueing the USB transfer.
Can you share an example use case for these new features? Is there a userspace that excercises the new ioctls?
We use it at Analog Devices to share buffers between the IIO subsystem and the USB stack, which makes it possible to stream data samples between a host computer and high-speed transceivers as fast as possible, in a zero-copy fashion.
This will be used by Libiio: https://github.com/analogdevicesinc/libiio/pull/928/commits/dd348137ce371532...
The code that uses these IOCTLs is not yet merged to the "master" branch, but will be as soon as this patchset is accepted.
Cheers, -Paul