From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Cc: Will Deacon <will.deacon@arm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Duyck <alexander.duyck@gmail.com>,
Sinan Kaya <okaya@codeaurora.org>, Arnd Bergmann <arnd@arndb.de>,
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: Aw: Re: RFC on writel and writel_relaxed
Date: Wed, 28 Mar 2018 21:20:16 +1100 [thread overview]
Message-ID: <1522232416.21446.10.camel@kernel.crashing.org> (raw)
In-Reply-To: <trinity-2ee224b5-cbac-415e-9f8c-305e802b5369-1522232002354@3c-app-gmx-bs61>
On Wed, 2018-03-28 at 12:13 +0200, Lino Sanfilippo wrote:
> Hi,
>
>
> >
> > Yeah so that other trick I'm talking about is also used for timing
> > accuracy.
> >
> > For example, let's say I have a device with a reset bit and the spec
> > says the reset bit needs to be set for at least 10us.
> >
> > This is wrong:
> >
> > writel(1, RESET_REG);
> > usleep(10);
> > writel(0, RESET_REG);
> >
> > Because of write posting, the first write might arrive to the device
> > right before the second one.
> >
>
> Does not write posting only concern PCI? This seems to be a different topic. Furthermore
> write posting should not include write reordering...
Nobody's talking about re-ordering and no, write posting is rather
common practice on a whole lot of different busses, not just PCI(e).
Cheers,
Ben.
next prev parent reply other threads:[~2018-03-28 10:38 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1521692689.16434.293.camel@kernel.crashing.org>
[not found] ` <CAOSf1CFv1HHCL3YOVhRn2U=grdNjaQ=A4m3xwxN2Rek1-_TySg@mail.gmail.com>
[not found] ` <1521726722.16434.312.camel@kernel.crashing.org>
[not found] ` <20180323163510.GC13033@ziepe.ca>
[not found] ` <1521854626.16434.359.camel@kernel.crashing.org>
[not found] ` <58ce5b83f40f4775bec1be8db66adb0d@AcuMS.aculab.com>
[not found] ` <20180326165425.GA15554@ziepe.ca>
[not found] ` <CAK8P3a1zeMyj+Z-y4ER4moY6Zip9EWNOinf+VnboGOrgiwbBZA@mail.gmail.com>
[not found] ` <20180326202545.GB15554@ziepe.ca>
[not found] ` <CAK8P3a3fc43ZcW626hmsd3DVcLw7hGkdUMxp7s4Rn3mdkziwMQ@mail.gmail.com>
[not found] ` <20180326210951.GD15554@ziepe.ca>
[not found] ` <CAK8P3a2UU1xAM0NLo7Q4-Xgo1SzY3De1uqpFudr+2ZW7nHEPmA@mail.gmail.com>
[not found] ` <1522101616.7364.13.camel@kernel.crashing.org>
2018-03-27 14:46 ` RFC on writel and writel_relaxed 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
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 [this message]
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
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