From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: RFC on writel and writel_relaxed
Date: Thu, 29 Mar 2018 02:13:16 +1100
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Cc: Alexander Duyck <alexander.duyck@gmail.com>,
        Will Deacon <will.deacon@arm.com>,
        Arnd Bergmann <arnd@arndb.de>, Jason Gunthorpe <jgg@ziepe.ca>,
        David Laight <David.Laight@aculab.com>,
        Oliver <oohall@gmail.com>,
        "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)"
        <linuxppc-dev@lists.ozlabs.org>, linux-rdma@vger.kernel.org,
        Alexander Duyck <alexander.h.duyck@redhat.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        netdev@vger.kernel.org, linus971@gmail.com
To: okaya@codeaurora.org,
        Linus Torvalds <torvalds@linux-foundation.org>
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On Wed, 2018-03-28 at 07:41 -0400, okaya@codeaurora.org wrote:
> Yes, we want to get there indeed. It is because of some arch not 
> implementing writel properly. Maintainers want to play safe.
> 
> That is why I asked if IA64 and other well known archs follow the 
> strongly ordered rule at this moment like PPC and ARM.
> 
> Or should we go and inform every arch about this before yanking wmb()?
> 
> Maintainers are afraid of introducing a regression.

Let's fix all archs, it's way easier than fixing all drivers. Half of
the archs are unused or dead anyway.

> > 
> > The above code makes no sense, and just looks stupid to me. It also
> > generates pointlessly bad code on x86, so it's bad there too.
> > 
> >                 Linus