Re: [PATCH 26/30] loongson: flush irq write operation

[Ralf Baechle <ralf@linux-mips.org>]

On Wed, May 20, 2009 at 10:28:14AM +0800, yanh wrote:

> I have test this patch just now. It works well on yeeloong. 

Thanks for testing.

> I have one question what's the difference between the two patch? 

Uncached writes can't be re-ordered.  By adding a read after the last
write my patch forces not only completion of the preceding write but due
to this ordering constraint also completion of all preceding writes is
enforced.

I/O space writes are slow.  I mean slower than slugs in space.  So my
patch is an optimization but that was not the point; I really only meant
to verify that we understood what's going on and we seem to.  Now let's
fix the real issue and make outX() non-posted.

  Ralf