From: Matt Porter <mporter@kernel•crashing.org>
To: Ralph Siemsen <rsiemsen@rossvideo•com>
Cc: ppcembed <linuxppc-embedded@ozlabs•org>
Subject: Re: 2.6 4xx GPIO OCP driver?
Date: Fri, 25 Feb 2005 17:29:41 -0700 [thread overview]
Message-ID: <20050225172941.A30499@cox.net> (raw)
In-Reply-To: <421F966D.4060206@rossvideo.com>; from rsiemsen@rossvideo.com on Fri, Feb 25, 2005 at 04:19:41PM -0500
On Fri, Feb 25, 2005 at 04:19:41PM -0500, Ralph Siemsen wrote:
> Matt Porter wrote:
>
> > I didn't bother merging it upstream at one time. It wasn't clear
> > if the driver had any value over just mmaping /dev/mem to bang
> > on the couple gpio registers directly. [...]
>
> Will that work on the 440 where the devices sit above 4GB mark? Or must
> one rely on there being an existing TLB mapping to bring them into
> 32-bit space?
Ack...that's the one thing we are missing. :-/ I had forgotten
that driver/char/mem.c calls remap_pfn_range() directly rather
than io_remap_page_range(). Had it called the latter, we'd be OK
since the "bigphys" fixup could take place. We can fix /dev/mem to
call io_remap_page_range() when on ppc32 && 36-bit phys...other arches
do similar tricks in that driver.
If everybody is happy with mmaping /dev/mem then we can go try that
route.
-Matt
next prev parent reply other threads:[~2005-02-26 0:30 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-25 19:40 2.6 4xx GPIO OCP driver? Steven Blakeslee
2005-02-25 20:25 ` Travis B. Sawyer
2005-02-25 20:30 ` Matt Porter
2005-02-25 20:51 ` Travis B. Sawyer
2005-02-25 21:19 ` Ralph Siemsen
2005-02-26 0:29 ` Matt Porter [this message]
2005-02-26 22:31 ` Travis Sawyer
2005-02-26 22:31 ` Travis B. Sawyer
-- strict thread matches above, loose matches on Subject: below --
2005-02-25 17:17 Travis B. Sawyer
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