On 03/08/2021 13:15, Arnd Bergmann wrote:
That seems reasonable. And asm-generic io.h should be ifdef'ed by
HAS_IOPORT. In your patch you had it under CONFIG_IOPORT - was that
intentional?
No, that was a typo. Thanks for pointing this out.
On another point, I noticed SCSI driver AHA152x depends on ISA, but is
not an isa driver - however it does use port IO. Would such dependencies
need to be changed to depend on HAS_IOPORT?
I'm not sure what you mean here. As far as I can tell, AHA152x is an ISA
driver in the sense that it is a driver for ISA add-on cards. However, it
is not a 'struct isa_driver' in the sense that AHA1542 is, AHA152x is even
older and uses the linux-2.4 style initialization using a module_init()
function that does the probing.
ok, fine. So I just wonder what the ISA kconfig dependency gets us for
aha152x. I experimented by removing the kconfig dependency and enabling
for the arm64 (which does not have CONFIG_ISA) std defconfig and it
built fine.
I did notice that arm32 support CONFIG_ISA - not sure why.
This is for some of the earlier machines we support:
mach-footbridge has some on-board ISA components, while
SA1100, PXA25x and S3C2410 each have at least one machine
with a PC/104 connector using ISA signaling for add-on cards.
There are also a couple of platforms with PCMCIA or CF slots
using the same ISA style I/O signals, but those have separate
drivers.
HARDCODED_IOPORT: (or another name you might think of,) Used by
drivers that unconditionally do inb()/outb() without checking the
validity of the address using firmware or other methods first.
depends on HAS_IOPORT and possibly architecture specific
settings.
Yeah, that sounds the same as what I was thinking. Maybe IOPORT_NATIVE
could work as a name. I would think that only x86/ia64 would define it.
A concern though is that someone could argue that is a functional
dependency, rather than just a build dependency.
You can have those on a number of platforms, such as early
PowerPC CHRP or pSeries systems, a number of MIPS workstations
including recent Loongson machines, and many Alpha platforms.
hmmm... if some machines under an arch support "native" port IO and some
don't, then if we use a common multi-platform defconfig which defines
HARDCODED_IOPORT, then we still build for platforms without "native"
port IO, which is not ideal.
Maybe the name should reflect that these all use PC-style ISA/LPC
port numbers without the ISA connectors.
Thanks,
john
