From: Dan Malek <dan@embeddededge.com>
To: Laurent Pinchart <laurent.pinchart@tbox.biz>
Cc: linuxppc-embedded@ozlabs.org
Subject: Re: Accessing the CPM2 on an MPC82xx : CPM_MAP_ADDR or cpm2_immr ?
Date: Thu, 2 Feb 2006 13:55:36 -0500 [thread overview]
Message-ID: <f23a702cbd0fc2910162c5cf25e30abe@embeddededge.com> (raw)
In-Reply-To: <200602021642.49282.laurent.pinchart@tbox.biz>
On Feb 2, 2006, at 10:42 AM, Laurent Pinchart wrote:
> The new fs_enet driver internally maps CPM_MAP_ADDR. Should every
> driver
> create an internal CPM mapping ?
Yes, they should. All drivers should do the ioremap() and stash the
pointer internally.
> .... Why was the old fec_enet driver able to
> access the CPM through CPM_MAP_ADDR without ioremap()ing it first ?
Because that's a long left over "performance hack" from many
years ago when I first implemented the 8xx software. The IMMR used
to be mapped to a well known virtual address, the board initialization
did this early, and everyone (ab)used it. This was way back in the
2.0/2.1
days when it was acceptable to do such things :-) Due to the CPM2 now
being used on may different Freescale parts, and mapped in various
ways, the internal mapping should be done by every driver.
Thanks.
-- Dan
prev parent reply other threads:[~2006-02-02 18:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-02 13:58 Accessing the CPM2 on an MPC82xx : CPM_MAP_ADDR or cpm2_immr ? Laurent Pinchart
2006-02-02 14:07 ` Vitaly Bordug
2006-02-02 15:42 ` Laurent Pinchart
2006-02-02 18:55 ` Dan Malek [this message]
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