linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
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


  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5e8dfbd2-a6c0-6d02-53e9-1f29aebcc44e@huawei.com \
    --to=john.garry@huawei.com \
    --cc=arnd@kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=schnelle@linux.ibm.com \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).