From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Duyck <alexander.duyck@gmail.com>,
Will Deacon <will.deacon@arm.com>,
Sinan Kaya <okaya@codeaurora.org>, Jason Gunthorpe <jgg@ziepe.ca>,
David Laight <David.Laight@aculab.com>, Oliver <oohall@gmail.com>,
"open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)"
<linuxppc-dev@lists.ozlabs.org>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: RFC on writel and writel_relaxed
Date: Wed, 28 Mar 2018 18:42:59 +1100 [thread overview]
Message-ID: <1522222979.7364.118.camel@kernel.crashing.org> (raw)
In-Reply-To: <CAK8P3a1QTjCtJMAv1RSN5ReiOShZ_ygkCXY484OJUvn6r+1mbg@mail.gmail.com>
On Wed, 2018-03-28 at 09:11 +0200, Arnd Bergmann wrote:
> On Wed, Mar 28, 2018 at 8:56 AM, Benjamin Herrenschmidt
> <benh@kernel.crashing.org> wrote:
> > On Wed, 2018-03-28 at 06:53 +0000, Linus Torvalds wrote:
> > > On Tue, Mar 27, 2018, 20:43 Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
> > > That's why in/out were *so* slow, and why nobody uses them any more
> > > (well, the address size limitations and the lack of any remapping of
> > > the address obviously also are a reason).
> >
> > All true indeed, though a lot of other archs never quite made them
> > fully synchronous, which was another can of worms ... oh well.
>
> Many architectures have no way of providing PCI compliant semantics
> for outb, as their instruction set and/or bus interconnect lacks a
> method of waiting for completion of an outb.
Yup, that includes powerpc. Note that since POWER8 we don't even
genetate IO space anymore :-)
> In practice, it doesn't seem to matter for any of the devices one would
> encounter these days: very few use I/O space, and those that do don't
> actually rely on the strict ordering. Some architectures (in particular
> s390, but I remember seeing the same thing elsewhere) explicitly
> disallow I/O space access on PCI because of this. On ARM, the typical
> PCI implementations have other problems that are worse than this
> one, so most drivers are fine with the almost-working semantics.
/me cries...
Ben.
next prev parent reply other threads:[~2018-03-28 8:23 UTC|newest]
Thread overview: 129+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-21 3:07 RFC on writel and writel_relaxed Sinan Kaya
2018-03-21 3:40 ` Oliver
2018-03-21 13:53 ` Sinan Kaya
2018-03-21 13:58 ` Sinan Kaya
2018-03-26 13:43 ` Arnd Bergmann
2018-03-26 16:00 ` Sinan Kaya
2018-03-21 14:35 ` David Laight
2018-03-21 15:04 ` Sinan Kaya
2018-03-22 5:24 ` Oliver
2018-03-22 8:20 ` Gabriel Paubert
2018-03-22 9:25 ` Oliver
2018-03-22 11:25 ` Gabriel Paubert
2018-03-22 10:37 ` David Laight
2018-03-22 4:24 ` Benjamin Herrenschmidt
2018-03-22 10:15 ` Oliver
2018-03-22 13:52 ` Benjamin Herrenschmidt
2018-03-22 17:51 ` Sinan Kaya
2018-03-23 0:16 ` Benjamin Herrenschmidt
2018-03-23 13:42 ` Sinan Kaya
2018-03-24 1:22 ` Benjamin Herrenschmidt
2018-03-24 15:06 ` Sinan Kaya
2018-03-26 11:44 ` Will Deacon
2018-03-26 12:11 ` okaya
2018-03-26 12:42 ` Sinan Kaya
2018-03-23 16:35 ` Jason Gunthorpe
2018-03-24 1:23 ` Benjamin Herrenschmidt
2018-03-26 11:08 ` David Laight
2018-03-26 16:54 ` Jason Gunthorpe
2018-03-26 19:44 ` Arnd Bergmann
2018-03-26 20:25 ` Jason Gunthorpe
2018-03-26 20:43 ` Arnd Bergmann
2018-03-26 21:09 ` Jason Gunthorpe
2018-03-26 21:30 ` Arnd Bergmann
2018-03-26 21:46 ` Sinan Kaya
2018-03-26 22:01 ` Benjamin Herrenschmidt
2018-03-26 22:08 ` Sinan Kaya
2018-03-26 22:28 ` Benjamin Herrenschmidt
2018-03-26 22:27 ` Jason Gunthorpe
2018-03-26 22:36 ` Benjamin Herrenschmidt
2018-03-26 22:42 ` Benjamin Herrenschmidt
2018-03-26 22:50 ` Jason Gunthorpe
2018-03-26 23:59 ` Benjamin Herrenschmidt
2018-03-27 1:39 ` Jason Gunthorpe
2018-03-27 7:56 ` Arnd Bergmann
2018-03-27 8:56 ` Benjamin Herrenschmidt
2018-03-27 9:44 ` Arnd Bergmann
2018-03-27 10:00 ` Will Deacon
2018-03-27 11:23 ` Benjamin Herrenschmidt
2018-03-27 12:22 ` okaya
2018-03-27 14:12 ` Jason Gunthorpe
2018-03-27 21:27 ` Benjamin Herrenschmidt
2018-03-27 9:57 ` Will Deacon
2018-03-27 10:05 ` Arnd Bergmann
2018-03-27 10:09 ` Will Deacon
2018-03-27 10:53 ` Arnd Bergmann
2018-03-27 11:02 ` Will Deacon
2018-03-27 11:05 ` Arnd Bergmann
2018-03-27 11:25 ` Benjamin Herrenschmidt
2018-03-27 13:20 ` David Laight
2018-03-27 13:46 ` Sinan Kaya
2018-03-27 14:36 ` Will Deacon
2018-03-27 21:29 ` Benjamin Herrenschmidt
2018-03-28 8:53 ` Will Deacon
2018-03-28 9:00 ` David Laight
2018-03-28 9:09 ` Will Deacon
2018-03-28 9:56 ` Benjamin Herrenschmidt
2018-03-28 9:50 ` Benjamin Herrenschmidt
2018-03-28 9:55 ` Arnd Bergmann
2018-03-28 10:01 ` Benjamin Herrenschmidt
2018-03-28 10:13 ` Will Deacon
2018-03-28 16:57 ` Jason Gunthorpe
2018-03-29 9:19 ` Will Deacon
2018-03-29 14:45 ` Jason Gunthorpe
2018-03-29 14:58 ` David Laight
2018-03-29 16:40 ` Jason Gunthorpe
2018-03-27 21:24 ` Benjamin Herrenschmidt
2018-03-27 11:21 ` Benjamin Herrenschmidt
2018-03-27 9:42 ` Will Deacon
2018-03-27 11:20 ` Benjamin Herrenschmidt
2018-03-27 11:24 ` Will Deacon
2018-03-27 14:24 ` Jason Gunthorpe
2018-03-27 14:16 ` Jason Gunthorpe
2018-03-26 22:00 ` Benjamin Herrenschmidt
2018-03-27 14:46 ` Sinan Kaya
2018-03-27 15:01 ` Jose Abreu
2018-03-27 15:10 ` Will Deacon
2018-03-27 18:54 ` Alexander Duyck
2018-03-27 19:54 ` Arnd Bergmann
2018-03-27 20:46 ` Arnd Bergmann
2018-03-27 21:33 ` Benjamin Herrenschmidt
2018-03-28 0:39 ` Linus Torvalds
2018-03-28 1:03 ` Benjamin Herrenschmidt
2018-03-28 2:51 ` Linus Torvalds
2018-03-28 3:24 ` Sinan Kaya
2018-03-28 4:41 ` Benjamin Herrenschmidt
2018-03-28 6:14 ` Linus Torvalds
2018-03-28 11:41 ` okaya
2018-03-28 15:13 ` Benjamin Herrenschmidt
2018-03-28 15:55 ` David Miller
2018-03-28 16:23 ` Nicholas Piggin
2018-03-28 21:31 ` Benjamin Herrenschmidt
2018-03-28 22:09 ` Nicholas Piggin
2018-03-29 9:20 ` Will Deacon
2018-03-29 13:56 ` Sinan Kaya
2018-03-29 14:04 ` David Miller
2018-03-29 16:29 ` Arnd Bergmann
2018-03-29 16:59 ` Sinan Kaya
2018-03-30 1:40 ` Benjamin Herrenschmidt
2018-04-02 13:01 ` Sinan Kaya
2018-03-28 4:33 ` Benjamin Herrenschmidt
2018-03-28 6:26 ` Linus Torvalds
2018-03-28 6:42 ` Benjamin Herrenschmidt
2018-03-28 6:53 ` Linus Torvalds
2018-03-28 6:56 ` Benjamin Herrenschmidt
2018-03-28 7:11 ` Arnd Bergmann
2018-03-28 7:42 ` Benjamin Herrenschmidt [this message]
2018-03-28 9:07 ` Will Deacon
2018-03-28 9:56 ` Benjamin Herrenschmidt
2018-03-28 10:13 ` Aw: " Lino Sanfilippo
2018-03-28 10:20 ` Benjamin Herrenschmidt
2018-03-28 11:30 ` David Laight
2018-03-28 15:12 ` Benjamin Herrenschmidt
2018-03-28 16:16 ` David Laight
2018-03-28 1:21 ` Benjamin Herrenschmidt
2018-03-27 21:35 ` Benjamin Herrenschmidt
2018-03-26 21:26 ` Benjamin Herrenschmidt
-- strict thread matches above, loose matches on Subject: below --
2018-03-27 21:54 Alexander Duyck
2018-03-27 22:35 ` Sinan Kaya
2018-03-27 23:43 ` Benjamin Herrenschmidt
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