On 4/7/23 14:01, Maciej W. Rozycki wrote: > On Fri, 7 Apr 2023, Sam Ravnborg wrote: > >>>> Randy's suggestion is fine, as we avoid building parport support >>>> for sparc32. If someone shows up and need parport support >>>> for sparc32 then we could look into how to enable it. >>>> Until then, we are better helped avoiding building the driver. >>> >>> I disagree. Why artificially prevent perfectly good hardware from >>> working with a perfectly good driver especially as the fix is just a >>> trivial exercise? And I offered a solution. >> >> There is no sparc32 with a PC style parallel port, so the parport_pc >> have no value for a sparc32 machine. > > There are PC-style PCI (and PCIe) parallel ports in the form of option > cards being sold; I have one in my RISC-V machine (and I had to go through > the hassle of figuring out why the heck I am not able to select the driver > in configuration; a situation analogous to what Randy's change wants to > arrange). You can plug one into any machine that has PCI slots and my > understanding from Linux Kconfig files is there are such 32-bit SPARC > machines in existence or the dependency on PCI wouldn't offer the driver. > Otherwise just don't enable CONFIG_PCI for 32-bit SPARC. > If there are 32-bit Sparc machines with PCI slots, we must not have any users with parallel ports or we should have heard about it IMO. > Apologies if I wasn't clear enough with my reasoning, although I think > the lone presence of the PCI dependency in Kconfig ought have to make it > clear. > >> The sparc32 machines have the parport_sunbpp driver for their parallel >> port. > > That's an onboard device or an SBus option card though, right? > >> An alternative fix, and better I think, would be to audit all archs >> and let the relevant ones select ARCH_MIGHT_HAVE_PC_PARPORT, so we >> avoided the ugly "|| (PCI && !S390 && !SPARC32)" case for PARPORT_PC. > > It's only S390 that is special in that it has a limited set of specially > crafted PCI options it can ever support (or so I am told; something about > the firmware or suchlike). >From my reading, if a Sparc32 machine has a PCI port, it might be able to have a parallel port. However, even with Maciej's suggested code change instead of my patch, the ebus code is not being compiled for Sparc32 -- only for Sparc64, so more changes are needed beyond Maciej's suggestion. But the documentation that I found refers to Ebus on Sparc4 machines. > Any other platform that has PCI slots will handle PC-style PCI parallel > port option cards just fine, as long as it supports PCI I/O read/write > commands (some systems such as POWER9 machines don't; Niklas Schnelle has > been recently working on a generic way to exclude drivers for devices that > require PCI port I/O from being offered with systems that have no support > for PCI port I/O). > > Let me know if you find anything here unclear or have any other questions > or comments. /me wishes that we had a Sparc maintainer. -- ~Randy
