From: Eugene Surovegin <ebs@ebshome.net>
To: David Hawkins <dwh@ovro.caltech.edu>
Cc: linuxppc-embedded@ozlabs.org
Subject: Re: Yosemite/440EP why are readl()/ioread32() setup to readlittle-endian?
Date: Wed, 1 Feb 2006 10:11:06 -0800 [thread overview]
Message-ID: <20060201181106.GA24138@gate.ebshome.net> (raw)
In-Reply-To: <43E0F81F.4050005@ovro.caltech.edu>
On Wed, Feb 01, 2006 at 10:04:15AM -0800, David Hawkins wrote:
> Matt,
>
> In the same vein as the readl()/writel() question, what
> are the assumptions regarding memcpy_toio and memcpy_fromio?
>
> If the memcpy_to/fromio operations are intended only
> for access to PCI devices, then they should also inherently
> perform little-endianness conversion. For the test driver
> I was working on, I did *not* find this the case, eg.
> I implemented the test driver read() and write() using the
> memcpy_to/fromio calls, and the data transfers occur
> in big-endian (well, 'native' mode, since I also test the
> same test driver with the PCI adapter in an x86 system).
>
> If memcpy_to/fromio can be used in a more general context,
> then I can see why they operate in native mode.
>
> Just looking for enlightenment.
This commands IIRC are intended for copying chunk of _bytes_. There
are no issues with endianess for bytes, e.g. they work just like
ordinary memcpy.
--
Eugene
next prev parent reply other threads:[~2006-02-01 18:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-01 11:19 Yosemite/440EP why are readl()/ioread32() setup to readlittle-endian? Jenkins, Clive
2006-02-01 17:02 ` David Hawkins
2006-02-01 17:44 ` Matt Porter
2006-02-01 17:53 ` David Hawkins
2006-02-01 18:04 ` David Hawkins
2006-02-01 18:11 ` Eugene Surovegin [this message]
2006-02-01 18:20 ` David Hawkins
2006-02-01 18:23 ` Eugene Surovegin
2006-02-01 21:14 ` Peter Korsgaard
2006-02-02 0:54 ` Kumar Gala
2006-02-02 3:07 ` Matt Porter
2006-02-02 8:09 ` Peter Korsgaard
2006-02-02 9:08 ` Eugene Surovegin
2006-02-02 17:34 ` Dale Farnsworth
2006-02-02 14:21 ` Matt Porter
-- strict thread matches above, loose matches on Subject: below --
2006-02-01 18:35 Jenkins, Clive
2006-02-01 20:35 ` David Hawkins
2006-02-02 9:35 Jenkins, Clive
2006-02-02 9:46 ` Eugene Surovegin
2006-02-02 14:37 ` Matt Porter
2006-02-02 17:45 ` Eugene Surovegin
2006-02-02 18:16 ` Matt Porter
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