Re: [RFC v2 30/39] scsi: add HAS_IOPORT dependencies

Arnd Bergmann
2022-05-04T21:36:04Z

On Wed, May 4, 2022 at 10:42 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Fri, Apr 29, 2022 at 03:50:51PM +0200, Niklas Schnelle wrote:
> > In a future patch HAS_IOPORT=n will result in inb()/outb() and friends
> > not being declared. We thus need to add HAS_IOPORT as dependency for
> > those drivers using them.
>
> Some of these drivers support devices using either I/O ports or MMIO.
> Adding the HAS_IOPORT dependency means MMIO devices that *could* work
> on systems without I/O ports, won't work.
>
> Even the MMIO-only devices are probably old and not of much interest.
> But if you want to disable them even though they *could* work, I think
> that's worth mentioning in the commit log.

I think this would again make more sense with the original CONFIG_LEGACY_PCI
conditional than the generic HAS_IOPORT one. I don't remember what the
objection was to that symbol.

I think the presence of inb()/outb() is a good indication that a driver is for
obsolete hardware, though of course there are important exceptions to this
that instead need to have the conditional in the code itself (8250,
vga, ipmi, ...)

Arnd