From: Timur Tabi <timur@freescale.com>
To: Scott Wood <scottwood@freescale.com>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: [PATCH 2/5] [POWERPC] QE: add support for QE USB clocks routing
Date: Thu, 17 Apr 2008 15:17:38 -0500 [thread overview]
Message-ID: <4807B062.3080004@freescale.com> (raw)
In-Reply-To: <4807AF9F.4060603@freescale.com>
Scott Wood wrote:
> That's implementation dependent, and support for accesses to uncached
> memory is being phased out of book E according to the E500 manual.
What's wrong with uncached memory?
>> The reservation is held within the processor, so it should work on I/O.
>
> Even if the core supports lwarx/stwcx to uncached memory, the I/O bus
> must support atomic read-modify-write transactions for this to work.
Why? I thought the way that lwarx/stwcx work is that since the processor
detects the reservation collision, and the processor is one doing the writes,
that it would know when the reservation collided. Why does the I/O bus need to
know anything?
> Why do you think you need lwarx/stwcx to I/O?
I figured that if I could use lwarx/stwcx to make clrsetbits atomic, there would
be no need to spinlocks protecting an individual register.
--
Timur Tabi
Linux kernel developer at Freescale
next prev parent reply other threads:[~2008-04-17 20:17 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-17 19:26 [PATCH 0/5] Few more patches for Kumar's powerpc.git Anton Vorontsov
2008-04-17 19:28 ` [PATCH 1/5] [POWERPC] sysdev: implement FSL GTM support Anton Vorontsov
2008-04-17 22:47 ` Anton Vorontsov
2008-04-18 4:19 ` Kumar Gala
2008-04-18 9:54 ` Anton Vorontsov
2008-04-17 19:28 ` [PATCH 2/5] [POWERPC] QE: add support for QE USB clocks routing Anton Vorontsov
2008-04-17 19:56 ` Timur Tabi
2008-04-17 19:59 ` Scott Wood
2008-04-17 20:04 ` Timur Tabi
2008-04-17 20:14 ` Scott Wood
2008-04-17 20:17 ` Timur Tabi [this message]
2008-04-17 20:26 ` Scott Wood
2008-04-17 20:47 ` Dale Farnsworth
2008-04-17 20:49 ` Timur Tabi
2008-04-17 20:54 ` Dale Farnsworth
2008-04-17 21:48 ` Anton Vorontsov
2008-04-17 22:00 ` Timur Tabi
2008-04-17 19:28 ` [PATCH 3/5] [POWERPC] QE: split par_io_config_pin() Anton Vorontsov
2008-04-17 21:53 ` Kumar Gala
2008-04-17 22:35 ` Anton Vorontsov
2008-04-17 19:29 ` [PATCH 4/5] [POWERPC] QE: implement support for the GPIO LIB API Anton Vorontsov
2008-04-17 22:35 ` Kumar Gala
2008-04-17 22:41 ` Anton Vorontsov
2008-04-18 2:21 ` Kumar Gala
2008-04-17 19:29 ` [PATCH 5/5] [POWERPC] 83xx: new board support: MPC8360E-RDK Anton Vorontsov
-- strict thread matches above, loose matches on Subject: below --
2008-04-18 19:06 [PATCH 0/5 v2] Few more patches for Kumar's powerpc.git Anton Vorontsov
2008-04-18 19:09 ` [PATCH 2/5] [POWERPC] QE: add support for QE USB clocks routing Anton Vorontsov
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