On Wed, 2 Mar 2022, Icenowy Zheng wrote:

quoted

The only PCI platforms that actually can't make use of PC-style
parallel 
port hardware are those newer PCIe systems that have no support for
I/O 
cycles in the host bridge, required by such parallel ports.  Notably,
this includes the s390 arch, which has port I/O accessors that cause 
compilation warnings (promoted to errors with `-Werror'), and there
are 
other cases such as the POWER9 PHB4 device, though this one has
variable 
port I/O accessors that depend on the particular system.  Also it is
not 
clear whether the serial port side of devices enabled by
PARPORT_SERIAL 
uses port I/O or MMIO.  Finally Super I/O solutions are always either
ISA or platform devices.

Just spot this patch in linux-riscv mailing list, I think there's a
pending patchset that tries to add a HAS_IOPORT Kconfig option, which
can be used in this situation.

 Thanks for your input.

 That has been actually discussed already with a conclusion that more work 
is required to have HAS_IOPORT supported, see the thread starting from: 
<https://lore.kernel.org/lkml/CAMuHMdW-utcFzCZTgqONjxs=U662nF0=aBQu7Zi7FBQouwiA3g@mail.gmail.com/ (local)>. 
(there's a reference to the HAS_IOPORT patchset there as well).  Once that 
has been sorted configuration conditions for the parport driver can be 
updated accordingly.  For the time being the !S390 qualification should 
do.

  Maciej

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