Re: Question about UIO vs DT

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, May 15, 2025 at 04:45:23AM +0000, Kuninori Morimoto wrote:
> 
> Hi Greg / UIO / DT
> 
> I would like to ask about UIO vs DT.
> 
> If my understanding was correct, current UIO can use 1 IRQ / 1 reg per 1 UIO,
> but some device needs multi-IRQ/reg. In such case, we need to use
> multi-UIO. But it is not good much to DT rule. For example in case of
> the device which needs "2 regs 3 irqs". it will be
> 
> (A)	[1 reg, 1 IRQ] UIO
> (B)	[1 reg, 1 IRQ] UIO
> (C)	[0 reg, 1 IRQ] UIO
> 
> and (C) will be DT error. Is this known issue ? Do we have better solution ?

Yes, write a real driver for the device as obviously it is a complex one
and UIO shouldn't be used for it :)

What type of device is this that requires this type of hardware control
and why do you feel that UIO is the proper solution?

thanks,

greg k-h