From: Roland Dreier <rdreier@cisco.com>
To: David Miller <davem@davemloft.net>
Cc: Eric.Moore@lsi.com, linux-scsi@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: HELP: Is writeq an atomic operation??
Date: Fri, 02 May 2008 15:43:32 -0700 [thread overview]
Message-ID: <adaabj8499n.fsf@cisco.com> (raw)
In-Reply-To: <20080502.153210.122414532.davem@davemloft.net> (David Miller's message of "Fri, 02 May 2008 15:32:10 -0700 (PDT)")
> > Is a 64bit write to MMIO registers an atomic operation when using the
> > writeq API?
>
> The answer to this question this is platform dependent.
>
> On most 64-bit platforms, it is. On some 32-bit ones, it is not.
Are there any 32-bit platforms with writeq()? A quick grep suggests not.
Are there any 64-bit platforms where writeq() allows the MMIO to be
split into multiple cycles from the target device's view? I've been
coding assuming that at least no other MMIO writes will reach the device
in the middle of a writeq().
- R.
next prev parent reply other threads:[~2008-05-02 22:43 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <0631C836DBF79F42B5A60C8C8D4E822901047B1D@NAMAIL2.ad.lsil.com>
2008-05-02 22:32 ` HELP: Is writeq an atomic operation?? David Miller
2008-05-02 22:43 ` Roland Dreier [this message]
2008-05-02 22:49 ` David Miller
2008-05-02 22:49 ` Moore, Eric
2008-05-02 22:53 ` Roland Dreier
2008-05-02 23:13 ` Moore, Eric
2008-05-02 23:21 ` Roland Dreier
2008-05-02 23:31 ` Moore, Eric
2008-05-02 22:40 Moore, Eric
2008-05-02 22:46 ` Roland Dreier
2008-05-03 0:42 ` H. Peter Anvin
2008-05-03 14:35 ` Alan Cox
2008-05-03 17:40 ` H. Peter Anvin
2008-05-03 22:37 ` Benjamin Herrenschmidt
2008-05-04 17:01 ` Roland Dreier
2008-05-02 22:50 ` Andi Kleen
2008-05-02 23:03 ` Moore, Eric
2008-05-02 23:13 ` Andi Kleen
2008-05-02 23:04 ` Roland Dreier
2008-05-02 23:20 ` Moore, Eric
2008-05-03 0:10 ` Roland Dreier
2008-05-02 23:12 ` Jesse Barnes
2008-05-03 0:41 ` H. Peter Anvin
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