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Message-ID: <20101115115311.72429aa9@udp111988uds.am.freescale.net>
Date: Mon, 15 Nov 2010 11:53:11 -0600
From: Scott Wood <scottwood@...escale.com>
To: Kumar Gala <galak@...nel.crashing.org>
CC: Timur Tabi <timur.tabi@...il.com>, <dan.j.williams@...el.com>,
<linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] fsldma: add support to 36-bit physical address
On Mon, 15 Nov 2010 11:43:12 -0600
Kumar Gala <galak@...nel.crashing.org> wrote:
>
> On Nov 15, 2010, at 10:13 AM, Timur Tabi wrote:
>
> > On Mon, Nov 15, 2010 at 9:16 AM, Kumar Gala <galak@...nel.crashing.org> wrote:
> >
> >> The programming model (if you look at the free-space in the registers and data structures) supports a 64-bit address. I'm trying to avoid changing the driver in the future if we have >36-bit. However this is such a minor worry that I'll stop and just ack the patch as is.
> >
> > I must still be missing something. I'm looking at the description of
> > the SATR register in the MPC8572 RM, and it shows this:
> >
> > 0 - 3 | 4 - 5 | 6 | 7 | 8 - 11 | 12 - 15 | 16-21 | 22-31
> > --- | STFLOWLVL | SPCIORDER | SSME | STRANSINT | SREADTTYPE | --- | ESAD
> >
> > The most that we can extend ESAD to is 16 bits, for a total of a
> > 48-bit physical address. Where are the other 16 bits supposed to go?
>
> I was looking at the link addresses. I stand corrected so our max is 48-bits.
Looks like 42 bits -- just because bits 16-21 could be used to extend
ESAD doesn't mean that they have been.
-Scott
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