From: Risto Suominen <risto.suominen@gmail.com>
To: LinuxPPC-dev <LinuxPPC-dev@ozlabs.org>
Subject: Re: MACE DMA problem on Powermac 7300
Date: Mon, 7 Dec 2009 18:22:23 +0200 [thread overview]
Message-ID: <46e1c7760912070822o79380f03i8047cac5d4b7ac7d@mail.gmail.com> (raw)
In-Reply-To: <1260151424.2249.1.camel@pasglop>
Hi, Ben,
2009/12/7, Benjamin Herrenschmidt <benh@kernel.crashing.org>:
>
> Cache coherency bugs in the chipset or HW bugs in DBDMA, we've been
> seeing those on/off on those old apple chipsets...
>
> Try forcing a 32 bytes alignment ?
>
You're thinking of placing the DMA descriptors on different cache lines?
That's excactly what I did with de2104x. But it was easier, I think.
The chip handled its own DMA, and by writing a skip value to a
register... I don't know this GC DMA controller well enough and
haven't found the documentation either...
But I tried the de21041 board with unmodified driver on this 7300, and
it works. The problem was on a 5500.
Risto
prev parent reply other threads:[~2009-12-07 16:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-06 22:36 MACE DMA problem on Powermac 7300 Risto Suominen
2009-12-07 2:03 ` Benjamin Herrenschmidt
2009-12-07 16:22 ` Risto Suominen [this message]
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