On Fri, 01 Sep 2006 10:34:24 -0700
Roland Dreier <[email protected]> wrote:
> Andrew> What's __raw_writeq() supposed to do, anyway? On alpha
> Andrew> it's writeq() without an mb(). On parisc it's writeq()
> Andrew> only the data is byte-reversed. On sparc64() it's
> Andrew> incomprehensible. On everything else it's writeq().
>
> My understanding is that __raw_writeq() is like writeq() except not
> strongly ordered and without the byte-swap on big-endian
> architectures. The __raw_writeX() variants are convenient to avoid
> having to write inefficient code like writel(swab32(foo), ...) when
> talking to a PCI device that wants big-endian data. Without the raw
> variant, you end up with a double swap on big-endian architectures.
>
> sparc64 looks wrong, since __raw_writeq() seems identical to writeq(),
> which seems to imply it's going to swab what is stores.
>
OK. Can we please stop hacking around this in drivers and
a) work out what it's supposed to do
b) document that (Documentation/DocBook/deviceiobook.tmpl or code
comment or whatever)
c) tell arch maintainers?
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