On Wed, 2 Jun 2021, Michael Schmitz wrote:
Hi Geert,
Am 02.06.2021 um 19:09 schrieb Geert Uytterhoeven:
Hi Michael,
On Wed, Jun 2, 2021 at 7:21 AM Michael Schmitz <schmitzmic@xxxxxxxxx> wrote:
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@xxxxxxxxx>
Thanks for your patch!
--- 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.
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
+ }
#endif
#endif
Gr{oetje,eeting}s,
Geert
