Re: 2.6.18-rc5-mm1: drivers/infiniband/hw/amso1100/c2.c compile error

Andrew Morton
2006-09-01T18:29:43Z

On Fri, 01 Sep 2006 10:34:24 -0700
Roland Dreier <rdreier@cisco.com> 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?