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

[Grewstad]

Thanks. My research shows that no user-space application depends on
this driver. As you said, we cannot determine the subsystem without
knowing the actual end users.

Thanks,
Arihan Bhor

On Mon, Jun 1, 2026 at 5:59 PM Andrew Lunn <andrew at lunn.ch> wrote:
>
> 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