From: Matt Turner <mattst88@gmail.com>
To: Sinan Kaya <okaya@codeaurora.org>
Cc: linux-alpha <linux-alpha@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>, Timur Tabi <timur@codeaurora.org>,
sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Philippe Ombredanne <pombredanne@nexb.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Kate Stewart <kstewart@linuxfoundation.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2
Date: Tue, 8 May 2018 19:57:53 -0700 [thread overview]
Message-ID: <CAEdQ38GY9ZtNqOt1ZSetwZjyKAokY6-qEVy1t+t=_FEqx+-+zQ@mail.gmail.com> (raw)
In-Reply-To: <2fd54f7c-ff73-5935-a253-c924f4373cc6@codeaurora.org>
On Fri, Apr 20, 2018 at 9:20 AM, Sinan Kaya <okaya@codeaurora.org> wrote:
> Hi Matt,
>
> On 4/17/2018 2:43 PM, Sinan Kaya wrote:
>> 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.
>>
>
> Can you also queue this for 4.17?
>
> There are already drivers checked into 4.17 that dropped the unnecessary
> barriers.
>
> I really hate to see Alpha broken because of this.
Yes, I will pick it up for 4.17.
Thanks for the patch.
prev parent reply other threads:[~2018-05-09 2:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-16 22:16 [PATCH] alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2 Sinan Kaya
2018-04-17 18:43 ` Sinan Kaya
2018-04-20 16:20 ` Sinan Kaya
2018-05-01 22:48 ` Sinan Kaya
2018-05-09 2:57 ` Matt Turner [this message]
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