Re: [RFC] drivers/staging/axis-fifo: Looking for users

[Michal Simek]

Hi,

On 6/1/26 09:15, Grewstad wrote:
> Hi,
> The AXI Stream FIFO driver has been in staging since 2018. I was trying to
> understand whether there are real in-tree users of this hardware today, and
> what the expected direction for graduating the driver out of staging might be.
>
> The only in tree reference to this driver that i found is
> drivers/ethernet/xilinx/xilinx_axienet_main.c, which states:
>
>   * TODO:
>   *  - Add Axi Fifo support.
>
>  From this, it appears AXI Stream FIFO support may be used for some AXI
> Ethernet hardware configurations. However, I’m not sure whether there are
> any other in-tree users of the AXI Stream FIFO IP besides Ethernet, or
> whether Ethernet is the primary intended consumer.

It is clear that driver in current state can't be used with axi ethernet out of 
box because pretty much it is just about user interface for fifo via char device 
fops. But we are talking about the same IP used in specific scenario and this 
driver doesn't implement integration which can be used in ethernet driver.

> If there are no other in-tree users, it’s unclear whether this driver should
> remain a standalone staging driver or be integrated into a specific subsystem
> like networking.

I don't think you will find out any in-tree user because driver purpose is 
different. It is about providing a user way via char device to push data to axi 
streaming interface which can be consumed by user logic. It is generic way how 
to push data there without writing specialized kernel driver for custom HW.


> Can you let me know if there are any known in-tree users for this driver,
> whether it has a large enough user base to justify its existence in
> the kernel tree,
> and what the hardware's real use cases are?

I think this is leaf driver which provide a way to axi fifo streaming interface 
where stream is connected to custom HW which consumes it. I can understand that 
this can be very useful for a lot of people who wants to process data from user 
space via custom logic with using streaming interface.

And I don't have any issue to agree to move the driver out of staging to common 
location.

Thanks,
Michal