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Subject: Re: [PATCH] alpha: io: reorder barriers to guarantee writeX() and
 iowriteX() ordering #2
To:     linux-alpha@vger.kernel.org, arnd@arndb.de, timur@codeaurora.org,
        sulrich@codeaurora.org
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        Richard Henderson <rth@twiddle.net>,
        Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
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        Thomas Gleixner <tglx@linutronix.de>,
        Kate Stewart <kstewart@linuxfoundation.org>,
        linux-kernel@vger.kernel.org
References: <1523917017-28084-1-git-send-email-okaya@codeaurora.org>
From:   Sinan Kaya <okaya@codeaurora.org>
Message-ID: <b9d845ad-62af-d300-53d9-2b62f5da6c44@codeaurora.org>
Date:   Tue, 17 Apr 2018 14:43:01 -0400
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On 4/16/2018 6:16 PM, Sinan Kaya wrote:
> memory-barriers.txt has been updated with the following requirement.
> 
> "When using writel(), a prior wmb() is not needed to guarantee that the
> cache coherent memory writes have completed before writing to the MMIO
> region."
> 
> Current writeX() and iowriteX() implementations on alpha are not
> satisfying this requirement as the barrier is after the register write.
> 
> Move mb() in writeX() and iowriteX() functions to guarantee that HW
> observes memory changes before performing register operations.
> 
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  arch/alpha/kernel/io.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)

Sorry for catching this late but this also needs to go to 4.17 after
review.

I missed the writel() implementation on arch/alpha/kernel/io.c file
on my first patch.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.