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SubjectRe: [PATCH 53 of 53] ipath - add memory barrier when waiting for writes
On Mon, 2006-05-15 at 08:57 -0700, Roland Dreier wrote:
> > static void i2c_wait_for_writes(struct ipath_devdata *dd)
> > {
> > + mb();
> > (void)ipath_read_kreg32(dd, dd->ipath_kregs->kr_scratch);
> > }
> This needs a comment explaining why it's needed. A memory barrier
> before a readl() looks very strange since readl() should be ordered anyway.

Yeah. It's actually working around what appears to be a gcc bug if the
kernel is compiled with -Os. Ralph knows the details; he can give a
more complete answer.


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