From: Andrei Dolnikov <adolnikov@ru•mvista.com>
To: "Mark A. Greer" <mgreer@mvista•com>
Cc: David.Jenkins@emerson•com, linuxppc-dev@ozlabs•org
Subject: Re: [PATCH 1/5] PowerPC 74xx: Katana Qp device tree
Date: Tue, 04 Dec 2007 20:28:57 +0300 [thread overview]
Message-ID: <47558E59.4040107@ru.mvista.com> (raw)
In-Reply-To: <20071204012329.GA18903@mag.az.mvista.com>
Mark A. Greer wrote:
> On Tue, Dec 04, 2007 at 07:52:50AM +1100, Benjamin Herrenschmidt wrote:
>
>>> #address-cells = <1>;
>>> + #size-cells = <1>;
>>> + model = "Katana-Qp"; /* Default */
>>> + compatible = "emerson,Katana-Qp";
>>> + coherency-off;
>>> +
>>>
>> What do that mean (coherency-off) ?
>>
>> Somebody is trying again to use a 74xx with non cache coherent DMA ?
>>
>
> Hi Ben.
>
> I suspect Andrei got that from the prpmc2800 dts which I made so I'll
> jump in. (BTW, this is the same debate we have every year or two. :)
>
> By looking at the dts, that board has an mv64460 which has a couple
> issues when it comes to coherency (depending on the rev of the chip).
>
> One is about not being able to use DCBST instructions with coherency on
> and the other is about limiting the length of one of the traces (which
> at least one board manufacturer that I know of refuses to implement).
> The first one is supposed to be fixed by rev A1 of the part and the second
> is supposed to be fixed by rev B0 of the part. I don't know what rev(s)
> are on the board(s) Andrei is using. If its B0 or later, in theory, the
> part should work with coherency on.
>
> Andrei, have you tested with coherency on?
>
Yes, I tested it with "coherency on", but it didn't work.
I checked chip revisions on all boards I have and they all are >=
mv64_4_60 B0.
Emerson team working on U-Boot for KatanaQP (David Jenkins copied in cc)
notified that they have newer firmware version which makes "coherency
on" functional.
At the moment I have no more details on it, but I'll investigate this
issue soon and let you know all the details.
> --
> [snip errata]
> --
>
> So, the answer depends on what part & what rev of the part you have
> (e.g., the pegasos doesn't use the MPSC and apparently has the other
> issues worked around so it can turn on coherency but the prpmc2800
> doesn't so it needs coherency off).
>
> BTW, I haven't forgotten the inherent bug you described when coherency
> is off (/me too lazy to find link to the email) but AFAIK I've never run
> into it. However, if I turn on coherency and stress the PCI bus, it
> hangs (I can't even look at memory thru a bdi).
>
> Mark
>
Thanks,
Andrei.
next prev parent reply other threads:[~2007-12-04 17:28 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-29 15:07 [PATCH 0/5] PowerPC 74xx: Add Emerson Katana Qp support Andrei Dolnikov
2007-11-29 15:28 ` [PATCH 1/5] PowerPC 74xx: Katana Qp device tree Andrei Dolnikov
2007-12-03 1:50 ` David Gibson
2007-12-03 19:26 ` Jon Loeliger
2007-12-04 0:33 ` David Gibson
2007-12-04 13:14 ` Jon Loeliger
2007-12-04 2:10 ` Mark A. Greer
2007-12-04 2:50 ` David Gibson
2007-12-04 5:30 ` Mark A. Greer
2007-12-06 23:27 ` Mark A. Greer
2007-12-08 1:33 ` David Gibson
2007-12-10 17:17 ` Mark A. Greer
2007-12-10 21:18 ` Dale Farnsworth
2007-12-16 6:40 ` David Gibson
2007-12-18 16:38 ` Dale Farnsworth
2007-12-03 20:52 ` Benjamin Herrenschmidt
2007-12-04 1:23 ` Mark A. Greer
2007-12-04 2:14 ` Benjamin Herrenschmidt
2007-12-04 5:34 ` Mark A. Greer
2007-12-04 17:28 ` Andrei Dolnikov [this message]
2007-12-04 17:35 ` Mark A. Greer
2007-11-29 15:35 ` [PATCH 2/5] PowerPC 74xx: Minor updates to MV64x60 boot code Andrei Dolnikov
2007-12-11 23:50 ` Mark A. Greer
2007-11-29 15:39 ` [PATCH 3/5] PowerPC 74xx: Katana Qp bootwrapper Andrei Dolnikov
2007-12-12 0:13 ` Mark A. Greer
2007-11-29 15:42 ` [PATCH 4/5] PowerPC 74xx: Katana Qp base support Andrei Dolnikov
2007-12-03 20:54 ` Benjamin Herrenschmidt
2007-12-04 2:12 ` Mark A. Greer
2007-12-12 0:48 ` Mark A. Greer
2007-11-29 15:45 ` [PATCH 5/5] PowerPC 74xx: Katana Qp default config Andrei Dolnikov
-- strict thread matches above, loose matches on Subject: below --
2007-11-16 15:43 [PATCH 0/1] PowerPC 74xx: Add Emerson Katana Qp support Andrei Dolnikov
2007-11-16 16:12 ` [PATCH 1/5] PowerPC 74xx: Katana Qp device tree Andrei Dolnikov
2007-11-21 18:08 ` Vitaly Bordug
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