From: Segher Boessenkool <segher@kernel.crashing.org>
To: Scott Wood <scottwood@freescale.com>
Cc: linuxppc-dev@ozlabs.org, jgarzik@pobox.com, netdev@vger.kernel.org
Subject: Re: [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership.
Date: Thu, 3 May 2007 01:42:06 +0200 [thread overview]
Message-ID: <9403063bda028d0dfe9e5a05ceea4d7a@kernel.crashing.org> (raw)
In-Reply-To: <4638F734.2040809@freescale.com>
>>> And the driver is already ppc-specific; it uses in/out_be32.
>>
>> True, but its hidden behind the gfar_read/write accessors.
>>
>> Your change is a bit more blatant.
>
> Well, Segher doesn't want me to use iobarrier (because it's not I/O).
> Andy doesn't want me to use wmb() (because it's sync).
You should use wmb(), but unfortunately too strong
semantics are required for that (ordering wrt I/O)
so it's a full sync on PowerPC. I don't believe
a priori that that would be notably slower, but if
actually is, you could use eieio() I suppose since
you say the driver is powerpc specific -- but please
put a comment in the source code then saying why you
don't use wmb() there.
Segher
next prev parent reply other threads:[~2007-05-02 23:42 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-02 19:57 [PATCH v2] gianfar: Add I/O barriers when touching buffer descriptor ownership Scott Wood
2007-05-02 20:09 ` Kumar Gala
2007-05-02 20:12 ` Scott Wood
2007-05-02 20:20 ` Kumar Gala
2007-05-02 20:40 ` Scott Wood
2007-05-02 21:23 ` Kumar Gala
2007-05-02 21:30 ` Scott Wood
2007-05-03 2:10 ` Kumar Gala
2007-05-03 16:00 ` Scott Wood
2007-05-03 16:38 ` Segher Boessenkool
2007-05-02 23:42 ` Segher Boessenkool [this message]
2007-05-04 22:13 ` Linas Vepstas
2007-05-04 23:24 ` Olof Johansson
2007-05-05 0:41 ` Segher Boessenkool
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