Re: Linux 6.4.4 on m68k - Q40 - pata_falcon causes oops at boot time

[Finn Thain <fthain@linux-m68k.org>]

On Tue, 25 Jul 2023, Michael Schmitz wrote:

> Thanks William,
> 
> On 24/07/23 23:42, William R Sowerbutts wrote:
> >> I was left with the impression that the Q40 does not actually have the IDE
> >> controller on the ISA bus.
> > This is mistaken.
> >
> > IDE is definitely accessed over the ISA bus.
> >
> > There is some documentation on the Q40/Q60 hardware here:
> > http://www.q40.de/download/harddoc.pdf
> Noted - hadn't seen this one before.
> >
> > The motherboard integrates the CPU, DRAM, video DRAM and display controller,
> > audio DACs, RTC, interrupt controller, keyboard controller, and an LED
> > output.
> 
> No disk controller on the main board - that's where my error originated.
> 
> Note that this also means that the address hardcoded for IDE may be 
> incorrect (AFAIR, IDE cards could have their IO base reassigned by 
> firmware).
> 
> > There are two ISA slots where all other I/O devices are connected. These are
> > described (concisely!) on page 7 of the linked manual:
> >
> > 8-bit ISA I/O cycles are performed for CPU byte accesses to 0xFF400001 + 4 *
> > ISA address
> >
> > 16-bit ISA I/O cycles are performed for CPU word accesses to 0xFF400000 + 4
> > * ISA address
> >
> > 8-bit ISA memory cycles are performed for CPU byte accesses to 0xFF800001 +
> > 4 * ISA address
> >
> > 16-bit ISA memory cycles are performed for CPU word accesses to 0xFF800000 +
> > 4 * ISA address
> Yep, that much is evident from the Q40 address translation scheme. But a 
> similar sort of scheme is used on other m68k platforms to wire up 
> peripherals that were originally designed for Intel systems, and these 
> are not connected through an ISA bus.

I can't figure out why those platforms don't suffer from the same "double 
translation" problem that William described on q40.

> > I understand that the machines originally shipped with a 16-bit ISA card
> > based on the W83787IF "PC super I/O" chip, integrating a floppy controller,
> > IDE interface, game port, parallel port, and two 16550A UARTs.
> OK.
> >
> > My Q40 came without this card, so I am using a card based on the similar
> > W83757 chip (the serial ports are 16450 instead of 16550A, it doesn't
> > support
> > the fancy EPP/ECP parallel port modes).
> >
> >>>> It might be a good idea to verify that IDE works in v5.13
> >>> Yes, please do.
> > It did.
> >
> >> And please also verify it's broken after 44b1fbc0f5f30e66 was applied.
> > I will try to do that!
> 
> Probably just try v5.14 - in my tree, 44b1fbc0f5f30e66 came on top of 5.13-rc2
> so 5.14 ought to have it applied (but rather check, just the same).
> 

If git is an obstacle, one may obtain the 44b1fbc0f5f30e66 tree (as 
easily as the v5.14 tree) by clicking the 'download' button here: 
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=44b1fbc0f5f30e66