From: John Francis <johnfrancsis@yahoo.com>
To: Dan Malek <dan@mvista.com>
Cc: linuxppc-embedded@lists.linuxppc.org
Subject: Re: Using IDMA1 ( or IDMA2 ) on 860
Date: Mon, 20 Aug 2001 12:16:55 -0700 (PDT) [thread overview]
Message-ID: <20010820191655.27820.qmail@web20105.mail.yahoo.com> (raw)
In-Reply-To: <3B802482.80086FC8@mvista.com>
Dan,
>
> > /* 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
Thanks for all your help and education. One last
question on this, if I have a pointer that is returned
by doing ioremap_noncache() if I want to assign this
pointer in buffer descriptor setup should i be doing
__pa () correct? Will __pa() translate that address
back to the actual physical address?
John
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2001-08-20 19:16 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
2001-08-20 19:16 ` John Francis [this message]
2001-08-20 19:35 ` Dan Malek
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