On Wed, 23 Jan 2019, John Snow wrote:
I guess this is technically an external change in behavior... I have no
real read on if this will break anything for anyone, or if anyone was
even using it.
Currently nothing but the mips_fulong2e board seems to use this device and I
don't think there's anything even on that board that would depend on (or
would work with) legacy only IDE mode of this device but I could not find a
test image to try. That board seems to be quite unfinished, I've tried to get
it in better shape but haven't succeeded yet. So I don't think this change in
the IDE device would break anything for anyone as it does not seem to be
usable yet but I plan to use this IDE part in subsequent patches and PCI
native mode works better.
Any thoughts on why it's okay to switch?
As said above it's unlikely anyone would depend on it now and all drivers I
know about prefer native mode anyway so likely it would work better after
this change. If not and it turns out someone is using the current behaviour I
can look at implementing switching between the two modes but that would be
more difficult (the ISA ports would need to be mapped and unmapped based on
bits in PCI_PROG_INTERFACE but there's no API to do this currently,
ide/core.c only has ide_init_ioport to add mapping but not the counterpart to
remove it; this could be implemented but unless found to be needed it
probably does not worth it). So I suggest to switch based on that this is a
quite unused part that's not likely to break anything and if it still found
to break something I'll look at fixing it or it could be reverted, but I
don't want to spend time now on something that's not actually used.