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Message-ID: <20080804224309.77ffd28e@lxorguk.ukuu.org.uk>
Date: Mon, 4 Aug 2008 22:43:09 +0100
From: Alan Cox <alan@...rguk.ukuu.org.uk>
To: Sergei Shtylyov <sshtylyov@...mvista.com>
Cc: Robert Hancock <hancockr@...w.ca>,
Bartlomiej Zolnierkiewicz <bzolnier@...il.com>,
James Bottomley <James.Bottomley@...senpartnership.com>,
ksummit-2008-discuss@...ts.linux-foundation.org,
linux-kernel <linux-kernel@...r.kernel.org>,
linux-ide <linux-ide@...r.kernel.org>
Subject: Re: Kernel Summit request for Discussion of future of ATA (libata)
and IDE
> > newer controllers support the 32bit PIO data cycles. Most PCI controllers
> > it makes no speed difference but host bus controllers (especially
> > PIIX/ICH) really benefit.
> >
>
> In what way if there's no speed gain?
As in the numbers are the same before and after. The FIFO on the
controller is happily hiding the extra latencies I assume.
> >> supported. I couldn't track down where that bit was actually defined in
> >> the first place, all the way back to ATA-1 it seems to be indicated as
> >> reserved. Actually, I'm not sure why the drive cares in the first place,
> >> it would seem like a pure host controller issue..
> >>
> >
> > It goes back before IDE into the depths of the original compaq spec. When
> > you have a device wired basically directly to the ISA bus (original IDE)
> >
>
> ISA has only 8/16-bit data bus, so it could not have mattered
> there...
Depends what a 32bit I/O looks like on the 16bit bus - timing wise.
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