From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.ebshome.net (gate.ebshome.net [64.81.67.12]) (using TLSv1 with cipher EDH-RSA-DES-CBC3-SHA (168/168 bits)) (Client CN "gate.ebshome.net", Issuer "gate.ebshome.net" (not verified)) by ozlabs.org (Postfix) with ESMTP id C813368A02 for ; Thu, 2 Feb 2006 05:11:09 +1100 (EST) Date: Wed, 1 Feb 2006 10:11:06 -0800 From: Eugene Surovegin To: David Hawkins Subject: Re: Yosemite/440EP why are readl()/ioread32() setup to readlittle-endian? Message-ID: <20060201181106.GA24138@gate.ebshome.net> References: <35786B99AB3FDC45A8215724617919736D9217@gbrwgceumf01.eu.xerox.net> <43E0E9A7.4040508@ovro.caltech.edu> <20060201104405.C16064@cox.net> <43E0F81F.4050005@ovro.caltech.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <43E0F81F.4050005@ovro.caltech.edu> Cc: linuxppc-embedded@ozlabs.org List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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