netdev - Re: [PATCH 2/14] nes: device structures and defines

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Date:	Wed, 8 Aug 2007 15:28:33 +0200
From:	Michael Buesch <mb@...sch.de>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Jeff Garzik <jeff@...zik.org>, ggrundstrom@...effect.com,
	rdreier@...co.com, ewg@...ts.openfabrics.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH 2/14] nes: device structures and defines

On Wednesday 08 August 2007 15:08:28 Andi Kleen wrote:
> On Wed, Aug 08, 2007 at 03:02:35PM +0200, Michael Buesch wrote:
> > On Wednesday 08 August 2007 14:55:11 Andi Kleen wrote:
> > > On Wed, Aug 08, 2007 at 01:50:35PM +0200, Michael Buesch wrote:
> > > > On Wednesday 08 August 2007 14:38:10 Andi Kleen wrote:
> > > > > Jeff Garzik <jeff@...zik.org> writes:
> > > > > > > +			val, reg_index, addr, addr+4); */
> > > > > > > +	writel(cpu_to_le32(reg_index), addr);
> > > > > > > +	writel(cpu_to_le32(val),(u8 *)addr + 4);
> > > > > > 
> > > > > > wrong -- endian conversion macros not needed with writel()

> > Fact is that we do _not_ need cpu_to_le32 with writel.
> 
> We do on a big endian platform if the register is LE. I assume that's the case 
> on this hardware.

That is not true.
writeX does automatically convert to bus-endian.
Which, in case of the PCI bus, is little endian.
So if your register is LE (which it is most likely), you don't
need any conversion. If your register is BE (which I very much doubt),
then you need swab32().
In _no_ case you need cpu_to_xx().

-- 
Greetings Michael.
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