From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Roland Dreier <rdreier@cisco.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Jeff Garzik <jgarzik@pobox.com>
Subject: Re: [RFC] pata_icside driver
Date: Mon, 9 Apr 2007 09:44:48 +0100 [thread overview]
Message-ID: <20070409084447.GB28366@flint.arm.linux.org.uk> (raw)
In-Reply-To: <adahcrq550y.fsf@cisco.com>
On Mon, Apr 09, 2007 at 01:24:45AM -0700, Roland Dreier wrote:
> > 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...
Now that I've had some breakfast, yes.
In any case, active + recovery must never be greater than the cycle time.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
next prev parent reply other threads:[~2007-04-09 8:44 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
2007-04-09 8:44 ` Russell King [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070409084447.GB28366@flint.arm.linux.org.uk \
--to=rmk+lkml@arm.linux.org.uk \
--cc=akpm@linux-foundation.org \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=jgarzik@pobox.com \
--cc=linux-kernel@vger.kernel.org \
--cc=rdreier@cisco.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox