Re: [PATCH RFC 1/2] m68k: io_mm.h: conditionalize ISA address translation on Atari

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Hi Brad,

Am 05.06.2021 um 10:49 schrieb Brad Boyer:
On Fri, Jun 04, 2021 at 07:30:00PM +1200, Michael Schmitz wrote:
I'm still unsure whether changing the default branch for the sake of
fixing Atari behaviour is a sane idea - I was hoping for comments either
way.


You mean, what happens if a random m68k platform (other than amiga, atari
and q40) were to adopt CONFIG_ISA? I guess it would be nice if that would
'just work' but it's probably never going to be needed.

The NULL default was meant to catch incorrect use of config options related
to CONFIG_ISA. My repurposing the default branch for Atari's needs (no
translation for IDE) defeats that. But the chance that we run into such
incorrect use in the future are pretty slim indeed.

Well, we could in theory add a trex socket driver to get PCMCIA support
for the PowerBook 190 hardware. There was a driver for that in ppc for
the PowerBook 5300 which uses the same chipset. I believe the PCMCIA
drivers use these same macros in spite of not being considered ISA.

Correct - the PCMCIA device drivers use IO port addresses in the ISA port range.

I don't see anything in drivers/pcmcia that is obviously an m68k
system even though I'm pretty sure I remember discussions of supporting
such hardware in the past.

There's the APNE driver (Amiga PCMCIA NE2000 clone), which is already catered for by the current code in io_mm.h. I remember seeing patches for that driver that would allow support of a variant of the APNE card that were hard to integrate in the current NE clone code framework. Didn't consider adding another isa_type for that card at the time - I'll revisit these patches if I can find them again.

Supporting PB190 PCMCIA hardware requires adding a new isa_type and the corresponding IO translation cases. Not much more, for all I can see. Existing chipset drivers from other architectures ought to work already. Maybe add a specific block_input() hook as for APNE (but I surmise that might just be code duplication from generic code in lib8390.c - didn't check).

Not sure what card socket code the APNE driver uses - must be one of the generic variants from drivers/pcmcia. If your PB190 needs something not already in there, we'd need to add that as well.

Is PCMCIA support something we should also consider in all of this?

Absolutely.

Cheers,

	Michael



	Brad Boyer
	flar@xxxxxxxxxxxxx




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