[RFC] drivers/staging/axis-fifo: TODO file and subsystem direction

[Grewstad]

Dear Maintainers,

I am interested in contributing to the Xilinx AXI-Stream FIFO driver
located in drivers/staging/axis-fifo.

While reviewing the driver, I noticed that it does not currently
contain a TODO file describing the work required for graduation from
staging. I would like to create such a file, but before doing so I
would appreciate guidance on the expected long-term direction for the
driver.

The driver currently exposes a custom userspace ABI through a
miscdevice. While this provides a generic interface to the FIFO, it
does not integrate with existing kernel subsystem tooling. One possible
incremental improvement in this area could be a transition from
miscdevice to a proper character device (cdev) interface, to allow for
a more clearly defined and maintainable userspace ABI.

Some possible directions that came to mind are:

- UIO, if the intent is to provide userspace control over a generic
  AXI-stream FIFO with minimal kernel policy.
- IIO, for data acquisition or SDR-oriented applications that could
  benefit from existing buffer infrastructure and userspace tooling.
- Networking, for packet-oriented AXI-stream use cases.

Before drafting a TODO file and proposing patches, I would like to
understand whether there is a preferred subsystem model for this
hardware, or whether the current architecture is expected to remain in
place.

Any guidance would be greatly appreciated.

Thank you,

Arihan Bhor