From: David Hawkins <dwh@ovro•caltech.edu>
To: Bruce_Leonard@selinc•com
Cc: linuxppc-dev@lists•ozlabs.org
Subject: Re: MPC8308 bursting question
Date: Fri, 27 May 2011 07:26:37 -0700 [thread overview]
Message-ID: <4DDFB49D.8010104@ovro.caltech.edu> (raw)
In-Reply-To: <OF1B4E92C8.698C0AE4-ON8825789D.00209684-8825789D.002206EF@selinc.com>
Hi Bruce,
> This isn't really a Linux PPC question, but this is the smartest mailing
> list I know for asking PPC hardware questions, so here goes.
>
> We're using an MPC8308 and want to use the DMA engine to move data in and
> out of an FPGA hanging on the local bus. Our bandwidth/local bus burden
> calculations were done assuming that we could use bursting. So I've setup
> a UPM to do single beat and burst reads/writes. I've also configured my
> DMA TCD to use a data transfer size of 32-bytes when accessing the FPGA.
> The problem I'm having is I can't seem to get the UPM to ever trigger the
> burst write sequence using the DMA. Single beat reads and writes work
> okay, but no bursting. In fact, the only thing I've been able to find in
> the manual that causes a burst transaction is a cache line miss, which is
> wholly in the purview of the core and really does me no good.
>
> Does anyone know of any way (short of issuing a run command to the UPM via
> MxMR) to force a burst transaction on the 8308? Am I just being dumb and
> missing something totally fundamental?
Read my MPC8349EA UPM setup notes and see if you have used
similar settings (I assume the local bus UPMs are similar):
http://www.ovro.caltech.edu/~dwh/carma_board/carma_sys.pdf
Do you have a Modelsim simulation of your interface?
I have a VHDL bus-functional-model I wrote that I can
send you.
Cheers,
Dave
next prev parent reply other threads:[~2011-05-27 14:45 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-27 6:11 MPC8308 bursting question Bruce_Leonard
2011-05-27 14:26 ` David Hawkins [this message]
2011-05-27 20:29 ` Bruce_Leonard
2011-05-27 20:33 ` David Hawkins
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