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

[Andrew Lunn]

On Mon, Jun 01, 2026 at 11:35:14AM +0530, Grewstad wrote:
> On Mon, Jun 1, 2026 at 1:22 AM Andrew Lunn <andrew at lunn.ch> wrote:
> >
> >
> > In addition to what GregKH said, look at the vendor information:
> >
> > https://docs.amd.com/r/en-US/pg080-axi-fifo-mm-s/Core-Overview
> >
> >   The AXI4-Stream FIFO core was designed to provide memory-mapped
> >   access to an AXI4-Stream interface connected to other IP (such as
> >   the AXI Ethernet core). Systems must be built through the AMD
> >   Vivado™ Design Suite to attach the AXI4-Stream FIFO core, AXI
> >   Ethernet core ...
> >
> > when used for Ethernet, a uAPI is not needed. The FIFO driver would
> > just expose an kernel internal API the Ethernet driver would use. Are
> > there any Ethernet devices using it? Is there a driver for the AXI
> > Ethernet core?
> 
> As I said to Greg K-H, it's 'chameleon' hardware because we don't know
> what it'll be used for. It could be SDR or Ethernet or whatever it is
> programmed for. The main thing is that it is a streaming interface.
> But we cannot assume the use case.

Flip that around. What is it actually used for today? Make sure it has
the correct APIs needed for what it does now. New APIs can always be
added latter, especially if they are in-kernel, code to glue it to an
Ethernet driver for example. 

However, a grep for XIL_AXIS_FIFO suggests nothing in-kernel actually
uses it.

Are there any real users from user space? You talk about SDR, does GNU
Radio use it? Using what hardware?

If you have no idea how the code is used, you cannot say what the
correct interface is....

	Andrew