From: John Garry <john.garry@huawei.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
linux-arch <linux-arch@vger.kernel.org>,
linux-pci <linux-pci@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
Niklas Schnelle <schnelle@linux.ibm.com>
Subject: Re: [GIT PULL 1/2] asm-generic: rework PCI I/O space access
Date: Wed, 4 Aug 2021 08:55:38 +0100 [thread overview]
Message-ID: <5e8dfbd2-a6c0-6d02-53e9-1f29aebcc44e@huawei.com> (raw)
In-Reply-To: <CAK8P3a3B4FCaPPHhzBdpkv0fsjE0jREwGFCdPeHEDHxxRBEjng@mail.gmail.com>
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
next prev parent reply other threads:[~2021-08-04 7:56 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-02 13:47 [GIT PULL 1/2] asm-generic: rework PCI I/O space access Arnd Bergmann
2021-07-02 13:49 ` [GIT PULL 2/2] asm-generic: Unify asm/unaligned.h around struct helper Arnd Bergmann
2021-07-02 20:13 ` pr-tracker-bot
2021-07-02 19:42 ` [GIT PULL 1/2] asm-generic: rework PCI I/O space access Linus Torvalds
2021-07-03 12:12 ` Arnd Bergmann
2021-07-05 10:06 ` Arnd Bergmann
2021-08-03 9:46 ` John Garry
2021-08-03 10:06 ` Arnd Bergmann
2021-08-03 11:23 ` John Garry
2021-08-03 12:15 ` Arnd Bergmann
2021-08-04 7:55 ` John Garry [this message]
2021-08-04 8:52 ` Arnd Bergmann
2021-08-10 9:19 ` John Garry
2021-08-10 11:33 ` Arnd Bergmann
2021-09-03 8:31 ` Niklas Schnelle
2021-12-17 13:19 ` Niklas Schnelle
2021-12-17 13:32 ` Arnd Bergmann
2021-12-17 13:52 ` Niklas Schnelle
2021-12-17 14:05 ` Arnd Bergmann
2021-12-17 14:27 ` John Garry
2021-12-17 14:32 ` Arnd Bergmann
2021-12-17 15:27 ` John Garry
2021-12-17 15:55 ` Arnd Bergmann
2021-12-17 16:30 ` John Garry
2021-12-20 9:27 ` Niklas Schnelle
2021-12-21 16:48 ` John Garry
2021-12-21 16:57 ` Niklas Schnelle
2021-12-19 14:23 ` David Laight
2021-12-21 16:21 ` John Garry
2021-07-05 12:40 ` Niklas Schnelle
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