Re: [PATCH 20/32] rt2x00: byte ordering correctness

[Michael Buesch <mb@bu3sch.de>]

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On Friday 28 April 2006 15:46, you wrote:
> On Fri, Apr 28, 2006 at 03:42:29PM +0200, Michael Buesch wrote:
> > I guess you are confusing something here:
> > MMIO access versus values in structs (for example) that 
> > are accessed through DMA (for example).
> 
> so there's two general problems:
> 
>   mmio/pio   - linux expects the device to be le there by defalt and
>                {read,write}{b,s,l} do the switch automatically
>   dmaed data - you always need to switch data yourself, data is commonly
>   	       either be or le
> 
> now there's devices that are always be for mmio or can be switched to it
> during initialization.  For Linux you'd traditionally have to switch before
> calling {read,write}{b,s,l} or use the __raw_ version that have other issues.
> The ioread*/iowrite* APIs now have a BE version, too.
> 
> I've not heard about devices having this switch for dma payload, and it
> would be rather usual as large parts of it are determined by some on the
> wire protocol anyway.

bcm43xx has a switch for this in PIO mode.
But we are currently not using it, because it is a little
bit tricky to get right and I did not want to do such experiments
before 2.6.17.

-- 
Greetings Michael.

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