On Wed, 2 Jun 2021, Michael Schmitz wrote:

Hi Geert,

Am 02.06.2021 um 19:09 schrieb Geert Uytterhoeven:

quoted

Hi Michael,

On Wed, Jun 2, 2021 at 7:21 AM Michael Schmitz [off-list ref] wrote:

quoted

For multiplatform kernels where CONFIG_ATARI_ROM_ISA is not set,
at least isa_sex must be set correctly to allow for correct I/O
primitive selection in shared drivers.

Signed-off-by: Michael Schmitz <schmitzmic@gmail.com>

Thanks for your patch!

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--- a/arch/m68k/kernel/setup_mm.c
+++ b/arch/m68k/kernel/setup_mm.c

@@ -386,6 +386,10 @@ void __init setup_arch(char **cmdline_p)
                isa_type = ISA_TYPE_ENEC;
                isa_sex = 0;
        }
+#else
+       if (MACH_IS_ATARI) {
+               isa_sex = 0;

I find it strange that you set isa_sex, but not isa_type?

Yes, as I said this is only to ensure isa_sex has the correct value (0) so
isa_readw() resolves to in_le16() for the Atari IDE driver after the change at
the end of the first patch. Might have been better to rather say

int isa_sex=0;

at the start of setup_mm.c ... or rely on that variable being initialized as
zero anyway.

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However, this is inside the CONFIG_ISA && MULTI_ISA block, so what 
kind of ISA does this correspond to?

No ISA at all in that case, but since we have to route all readw() calls 
through isa_readw() for the sake of generality if we want to support Q40 
ISA and Atari MMIO in the same kernel image, we need to make sure 
isa_readw() does the right thing on Atari if CONFIG_ISA is set.

I know io_mm.h says it's about various ISA bridges, but as I found out, 
drivers using only MMIO are also affected by these definitions.

'Maze' does not begin to describe it, 'mess' might be getting closer, 
but I can't see how we would avoid use of definitions in io_mm.h by 
non-ISA drivers.

It seems that the need for explicit zero initialization has more to do 
with subtelty over in asm/io_mm.h than anything else. If so, it would be 
better to add commentary there than to add redundant code here.

Cheers,

	Michael

quoted

quoted

+       }
 #endif
 #endif

Gr{oetje,eeting}s,

                        Geert