From: Wolfgang Denk <wd@denx.de>
To: "Young-Han, Kim" <yhkim@da-san.com>
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: MPC 8xx as SPI slave...
Date: Wed, 26 Mar 2003 12:02:10 +0100 [thread overview]
Message-ID: <20030326110215.8C7ECC58BA@atlas.denx.de> (raw)
In-Reply-To: Your message of "Wed, 26 Mar 2003 18:44:17 +0900." <000901c2f37c$44a2a800$337ceccb@dasan.com>
Dear Kim,
in message <000901c2f37c$44a2a800$337ceccb@dasan.com> you wrote:
>
> Also, I was doubt the cache problem.
> I'll check again...
> My code is based on your lwmon_spi.c just basic function.
Note that there is also a simple (and more generic) SPI driver in
cpm_spi.c
> > Does the 8xx transfer data at all? You know, SPI has a very, very low
> > priority onthe CPM, so it will be starved by any other I/O (like
> > ethernet and especially USB).
>
> Just transmit the previous data of TX BD not on time.
> I'll check the priority...
Try reducing the SPI clock. You cannot change the priority of SPI in
the CPM - it is implemented in software (microcode), and running at
the lowest priority. It is not useful for any taks which needs to
transfer large amounts of data quickly.
Best regards,
Wolfgang Denk
--
Software Engineering: Embedded and Realtime Systems, Embedded Linux
Phone: (+49)-8142-4596-87 Fax: (+49)-8142-4596-88 Email: wd@denx.de
Those who do not understand Unix are condemned to reinvent it,
poorly. - Henry Spencer, University of Toronto Unix hack
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
prev parent reply other threads:[~2003-03-26 11:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-26 2:50 MPC 8xx as SPI slave Young-Han, Kim
2003-03-26 7:03 ` Wolfgang Denk
2003-03-26 9:44 ` Young-Han, Kim
2003-03-26 11:02 ` Wolfgang Denk [this message]
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