On Tue, 2023-11-21 at 11:03 +0100, Arnd Bergmann wrote: > On Mon, Nov 20, 2023, at 22:59, Philipp Stanner wrote: > > lib/iomap.c contains one of the definitions of pci_iounmap(). The > > current comment above this out-of-place function does not clarify > > WHY > > the function is defined here. > > > > Linus's detailed comment above pci_iounmap() in drivers/pci/iomap.c > > clarifies that in a far better way. > > > > Extend the existing comment with an excerpt from Linus's and hint > > at the > > other implementation in drivers/pci/iomap.c > > > > Signed-off-by: Philipp Stanner <pstanner@xxxxxxxxxx> > > I think instead of explaining why the code is so complicated > here, I'd prefer to make it more logical and not have to > explain it. > > We should be able to define a generic version like > > void pci_iounmap(struct pci_dev *dev, void __iomem * addr) > { > #ifdef CONFIG_HAS_IOPORT > if (iomem_is_ioport(addr)) { > ioport_unmap(addr); > return; > } > #endif > iounmap(addr) > } And where would you like such a function to reside? drivers/pci/iomap.c? P. > > and then define iomem_is_ioport() in lib/iomap.c for x86, > while defining it in asm-generic/io.h for the rest, > with an override in asm/io.h for those architectures > that need a custom inb(). > > Note that with ia64 gone, GENERIC_IOMAP is not at all > generic any more and could just move it to x86 or name > it something else. This is what currently uses it: > > arch/hexagon/Kconfig: select GENERIC_IOMAP > arch/um/Kconfig: select GENERIC_IOMAP > > These have no port I/O at all, so it doesn't do anything. > > arch/m68k/Kconfig: select GENERIC_IOMAP > > on m68knommu, the default implementation from asm-generic/io.h > as the same effect as GENERIC_IOMAP but is more efficient. > On classic m68k, GENERIC_IOMAP does not do what it is > meant to because I/O ports on ISA devices have port > numbers above PIO_OFFSET. Also they don't have PCI. > > arch/mips/Kconfig: select GENERIC_IOMAP > > This looks completely bogus because it sets PIO_RESERVED > to 0 and always uses the mmio part of lib/iomap.c. > > arch/powerpc/platforms/Kconfig: select GENERIC_IOMAP > > This is only used for two platforms: cell and powernv, > though on Cell it no longer does anything after the > commit f4981a00636 ("powerpc: Remove the celleb support"); > I think the entire io_workarounds code now be folded > back into spider_pci.c if we wanted to. > > The PowerNV LPC support does seem to still rely on it. > This tries to do the exact same thing as lib/logic_pio.c > for Huawei arm64 servers. I suspect that neither of them > does it entirely correctly since the powerpc side appears > to just override any non-LPC PIO support while the arm64 > side is missing the ioread/iowrite support. > > Arnd >