From: Dan Malek <dan@mvista.com>
To: John Francis <johnfrancsis@yahoo.com>
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: Using IDMA1 ( or IDMA2 ) on 860
Date: Sun, 19 Aug 2001 16:41:38 -0400 [thread overview]
Message-ID: <3B802482.80086FC8@mvista.com> (raw)
In-Reply-To: 20010819203359.28639.qmail@web20104.mail.yahoo.com
John Francis wrote:
> May be I should have been more specific, yes I have
> setup the PC15 pin to have correct direction.
Well, your description indicated you were expecting the
transition of DREQ to generate an interrupt. This isn't
the case. Have you connected a logic analyzer to the bus
and determined the DMA is working correctly?
> /* version2 of GetChipAddress this WORKS why? */
Because you can't directly access physical bus addresses from
the kernel. They have to be mapped to some virtual address.
The IMMR is mapped to a well known address that can generally
be used anywhere in the kernel. Anything else must be mapped,
as your example shows. Just make sure you do this _once_,
don't keep calling ioremap() over and over or you will exhaust
the VM space and get a different address every time.
-- Dan
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2001-08-19 20:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-08-19 19:06 Using IDMA1 ( or IDMA2 ) on 860 John Francis
2001-08-19 19:50 ` Dan Malek
2001-08-19 20:33 ` John Francis
2001-08-19 20:41 ` Dan Malek [this message]
2001-08-20 19:16 ` John Francis
2001-08-20 19:35 ` Dan Malek
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