From: Niklas Schnelle <schnelle@linux.ibm.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>,
"Maciej W. Rozycki" <macro@orcam.me.uk>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Sven Schnelle <svens@linux.ibm.com>,
Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Anton Ivanov <anton.ivanov@cambridgegreys.com>,
Chris Zankel <chris@zankel.net>,
Max Filippov <jcmvbkbc@gmail.com>,
linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org,
linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] parport_pc: Also enable driver for PCI systems
Date: Mon, 14 Feb 2022 09:37:43 +0100 [thread overview]
Message-ID: <e5ec2e3be2e70e690bd9112bd23297d05a2993e6.camel@linux.ibm.com> (raw)
In-Reply-To: <CAMuHMdW-utcFzCZTgqONjxs=U662nF0=aBQu7Zi7FBQouwiA3g@mail.gmail.com>
On Mon, 2022-02-14 at 09:20 +0100, Geert Uytterhoeven wrote:
> Hi Maciej,
>
> CC Niklas
>
> On Sun, Feb 13, 2022 at 1:45 PM Maciej W. Rozycki <macro@orcam.me.uk> wrote:
> > Nowadays PC-style parallel ports come in the form of PCI and PCIe option
> > cards and there are some combined parallel/serial option cards as well
> > that we handle in the parport subsystem. There is nothing in particular
> > that would prevent them from being used in any system equipped with PCI
> > or PCIe connectivity, except that we do not permit the PARPORT_PC config
> > option to be selected for platforms for which ARCH_MIGHT_HAVE_PC_PARPORT
> > has not been set for.
> >
> > 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. An example
> > of such a host bridge is the POWER9 PHB4 device, but it is an exception
> > rather than the norm. Also it is not clear whether the serial port side
>
> Note that this hardware dependency is being addressed in
> "[RFC 00/32] Kconfig: Introduce HAS_IOPORT and LEGACY_PCI options"
> https://lore.kernel.org/all/20211227164317.4146918-1-schnelle@linux.ibm.com/
Thanks, for Cc'ing me. Note that this series is currently in kind of a
hold as we haven't yet found a clear direction yet. There was some
clear opposition for the LEGACY_PCI option introduced in that series
and only little support for HAS_IOPORT.
>
> > --- linux-macro.orig/drivers/parport/Kconfig
> > +++ linux-macro/drivers/parport/Kconfig
> > @@ -42,7 +42,7 @@ if PARPORT
> >
> > config PARPORT_PC
> > tristate "PC-style hardware"
> > - depends on ARCH_MIGHT_HAVE_PC_PARPORT
> > + depends on ARCH_MIGHT_HAVE_PC_PARPORT || PCI
This would allow selecting PARPORT_PC on s390 e.g. for allyesconfig and
randconfig and like POWER9 we definitely do not support I/O port
access.
We will also get warnings when compiling with clang. A problem my
series was originally started to address. So I'd really like to see a
better solution here for such a change. With the HAS_IOPORT option from
my series this would be simple but we don't currently have that though
maybe this is also an argument for introducing HAS_IOPORT even if we
don't add the LEGACY_PCI option.
> > help
> > You should say Y here if you have a PC-style parallel port. All
> > IBM PC compatible computers and some Alphas have PC-style
> > @@ -77,7 +77,7 @@ config PARPORT_PC_FIFO
> >
> > config PARPORT_PC_SUPERIO
> > bool "SuperIO chipset support"
> > - depends on PARPORT_PC && !PARISC
> > + depends on ARCH_MIGHT_HAVE_PC_PARPORT && PARPORT_PC && !PARISC
> > help
> > Saying Y here enables some probes for Super-IO chipsets in order to
> > find out things like base addresses, IRQ lines and DMA channels. It
> >
>
> Gr{oetje,eeting}s,
>
> Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
next prev parent reply other threads:[~2022-02-14 8:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-13 12:45 [PATCH] parport_pc: Also enable driver for PCI systems Maciej W. Rozycki
2022-02-14 8:20 ` Geert Uytterhoeven
2022-02-14 8:37 ` Niklas Schnelle [this message]
2022-02-14 9:21 ` Maciej W. Rozycki
2022-02-14 9:53 ` Niklas Schnelle
2022-02-14 9:16 ` Maciej W. Rozycki
2022-02-14 10:04 ` Niklas Schnelle
2022-02-14 20:42 ` Maciej W. Rozycki
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