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From: Jes Sorensen <jes@sunsite.dk>
To: Johannes Erdfelt <johannes@erdfelt.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, linux-kernel@vger.kernel.org
Subject: Re: Determine if card is in 32 or 64 bit PCI slot?
Date: 14 Aug 2001 17:55:57 +0200	[thread overview]
Message-ID: <d3elqe63g2.fsf@lxplus015.cern.ch> (raw)
In-Reply-To: <20010808161703.Q21901@sventech.com> <E15UaNj-00062K-00@the-village.bc.nu> <20010808165919.R21901@sventech.com>
In-Reply-To: Johannes Erdfelt's message of "Wed, 8 Aug 2001 16:59:19 -0400"

>>>>> "Johannes" == Johannes Erdfelt <johannes@erdfelt.com> writes:

Johannes> On Wed, Aug 08, 2001, Alan Cox <alan@lxorguk.ukuu.org.uk>
Johannes> wrote:
>> Are you sure the card actually needs this. Most such cards support
>> dual address cycle, so when placed in a 32bit slot will still do
>> 64bit DMA

Johannes> No I don't know if it's needed. I had no idea that PCI could
Johannes> do that.

Johannes> Is dual address cycle mandated by the PCI specs?

According to the PCI spec "The master is required in all cases to use
two clocks to communicate a 64-bit address, since the width of a
target's bus is not known during the address phase."

Aka, the answer to your question is yes.

Jes

  reply	other threads:[~2001-08-14 18:39 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2001-08-08 20:17 Determine if card is in 32 or 64 bit PCI slot? Johannes Erdfelt
2001-08-08 20:56 ` Alan Cox
2001-08-08 20:59   ` Johannes Erdfelt
2001-08-14 15:55     ` Jes Sorensen [this message]
2001-08-14 16:29       ` Johannes Erdfelt
2001-08-09 18:44   ` disappearing cdrom on reboot with 2.4.7-ac10 David Flood

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