From: Roland Dreier <rdreier@cisco.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Jeff Garzik <jgarzik@pobox.com>
Subject: Re: [RFC] pata_icside driver
Date: Mon, 09 Apr 2007 01:24:45 -0700 [thread overview]
Message-ID: <adahcrq550y.fsf@cisco.com> (raw)
In-Reply-To: <20070409081824.GA28366@flint.arm.linux.org.uk> (Russell King's message of "Mon, 9 Apr 2007 09:18:24 +0100")
> Lets say that we want to do MW DMA mode 2. This has the minimum timing
> of 70ns active, 25ns recovery, 120ns cycle time.
>
> When you quantise those figures using a clock period of 62.5ns (16MHz)
> you end up with: 2 clocks active (2*62.5 > 70), 1 clock recovery
> (1*62.5 > 25) and 2 clocks cycle (2*62.5 > 120).
>
> Last time I checked, active + recovery must always be equal to the cycle
> time, and unless my math is failing me, 2 + 1 does not equal 2.
Do you mean active + recovery must be less than or equal to the cycle
time? Because 70ns + 25ns does not equal 120ns either...
- R.
next prev parent reply other threads:[~2007-04-09 8:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-30 11:00 [PATCH] Provide dummy devm_ioport_* if !HAS_IOPORT Russell King
2007-03-30 11:08 ` [RFC] pata_platform for ARM RiscPC Russell King
2007-04-08 10:18 ` [RFC] pata_icside driver Russell King
2007-04-08 18:59 ` Alan Cox
2007-04-09 1:03 ` Jeff Garzik
2007-04-09 9:56 ` Alan Cox
2007-04-09 10:56 ` Jeff Garzik
2007-04-09 11:13 ` Jeff Garzik
2007-04-09 11:36 ` Russell King
2007-04-09 12:02 ` Jeff Garzik
2007-04-08 20:09 ` Alan Cox
2007-04-09 8:18 ` Russell King
2007-04-09 8:24 ` Roland Dreier [this message]
2007-04-09 8:44 ` Russell King
2007-04-09 10:25 ` Alan Cox
2007-04-09 11:33 ` Russell King
2007-04-21 15:09 ` Russell King
2007-04-09 11:32 ` [RFC] pata_platform for ARM RiscPC Jeff Garzik
2007-03-30 11:08 ` [PATCH] Provide dummy devm_ioport_* if !HAS_IOPORT Christoph Hellwig
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