From: Arnd Bergmann <arnd@arndb.de>
To: Sergei Shtylyov <sshtylyov@mvista.com>
Cc: Paulius Zaleckas <paulius.zaleckas@gmail.com>,
Hans Ulli Kroll <ulli.kroll@googlemail.com>,
Russell King <linux@arm.linux.org.uk>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] ARM: Gemini: Add support for PCI BUS
Date: Mon, 6 Dec 2010 13:18:24 +0100 [thread overview]
Message-ID: <201012061318.24541.arnd@arndb.de> (raw)
In-Reply-To: <4CFCC048.4030408@ru.mvista.com>
On Monday 06 December 2010, Sergei Shtylyov wrote:
> > There are many differences between readl and __raw_readl, including
>
> > * __raw_readl does not have barriers and does not serialize with
> > spinlocks, so it breaks on out-of-order CPUs.
> > * __raw_readl does not have a specific endianess, while readl is
> > fixed little-endian,
>
> I know I'm late but readl()/writel() are CPU-endian, not LE.
If that was the case, it would be a bug. readl/writel is defined to be
the same endianess as PCI, which is little-endian. Otherwise you would
not be able to use any PCI devices on big-endian ARM machines. The
definition of readl is
#define readl(addr) __le32_to_cpu(__raw_readl(addr))
which converts the little-endian I/O register into a native endian
CPU register.
Arnd
next prev parent reply other threads:[~2010-12-06 12:20 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-27 12:24 [PATCH] ARM: Gemini: Add support for PCI BUS Hans Ulli Kroll
2010-11-28 19:56 ` Arnd Bergmann
2010-11-29 12:17 ` Hans Ulli Kroll
2010-11-29 15:02 ` Arnd Bergmann
2010-11-29 16:05 ` Paulius Zaleckas
2010-11-29 16:45 ` Arnd Bergmann
2010-11-29 18:52 ` Paulius Zaleckas
2010-11-29 20:02 ` Arnd Bergmann
2010-11-29 20:19 ` Paulius Zaleckas
2010-11-30 8:15 ` Hans Ulli Kroll
2010-11-30 9:34 ` Paulius Zaleckas
2010-12-01 11:52 ` Hans Ulli Kroll
2010-12-01 13:08 ` Paulius Zaleckas
2010-12-01 15:02 ` Hans Ulli Kroll
2010-12-06 10:51 ` Sergei Shtylyov
2010-12-06 12:18 ` Arnd Bergmann [this message]
2010-11-29 19:32 ` Russell King - ARM Linux
2010-11-29 19:57 ` Paulius Zaleckas
-- strict thread matches above, loose matches on Subject: below --
2010-11-20 14:27 [PATCH] ARM: Gemini: Add support for PCI Bus Hans Ulli Kroll
2010-11-20 19:30 ` Paulius Zaleckas
2010-11-26 11:18 ` Russell King - ARM Linux
2010-11-26 11:57 ` Michał Mirosław
2010-11-27 12:16 ` Hans Ulli Kroll
2010-11-27 13:01 ` Michał Mirosław
2010-11-27 15:39 ` Arnd Bergmann
2010-11-29 8:12 ` Hans Ulli Kroll
2010-11-29 14:22 ` Russell King - ARM Linux
2010-11-29 14:50 ` Hans Ulli Kroll
2010-11-29 15:57 ` Arnd Bergmann
2010-11-30 15:38 ` Hans Ulli Kroll
2010-11-30 16:05 ` Russell King - ARM Linux
2010-11-30 16:19 ` Arnd Bergmann
2010-12-01 15:05 ` Hans Ulli Kroll
2010-11-29 15:50 ` Arnd Bergmann
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