From: Bagas Sanjaya <bagasdotme@gmail.com>
To: Parav Pandit <parav@nvidia.com>,
arnd@arndb.de, stern@rowland.harvard.edu, parri.andrea@gmail.com,
will@kernel.org, peterz@infradead.org, boqun.feng@gmail.com,
npiggin@gmail.com, dhowells@redhat.com, j.alglave@ucl.ac.uk,
luc.maranget@inria.fr, paulmck@kernel.org, akiyks@gmail.com,
dlustig@nvidia.com, joel@joelfernandes.org, corbet@lwn.net,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linux-doc@vger.kernel.org
Subject: Re: [PATCH v2] locking/memory-barriers.txt: Improve documentation for writel() example
Date: Thu, 6 Oct 2022 09:00:50 +0700 [thread overview]
Message-ID: <a938dcae-0f0c-e99c-7217-29e52a4b2052@gmail.com> (raw)
In-Reply-To: <20221005104749.157444-1-parav@nvidia.com>
On 10/5/22 17:47, Parav Pandit wrote:
> @@ -1927,10 +1927,12 @@ There are some more advanced barrier functions:
> before we read the data from the descriptor, and the dma_wmb() allows
> us to guarantee the data is written to the descriptor before the device
> can see it now has ownership. The dma_mb() implies both a dma_rmb() and
> - a dma_wmb(). Note that, 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. The cheaper writel_relaxed() does not provide
> - this guarantee and must not be used here.
> + a dma_wmb(). Note that, when using writel(), a prior barrier is not
> + needed to guarantee that the cache coherent memory writes have completed
> + before writing to the MMIO region. The cheaper writel_relaxed() does not
> + provide this guarantee and must not be used here. Hence, writeX() is always
> + preferred which inserts needed platform specific barrier before writing to
> + the specified MMIO region.
>
Did you mean that writeX() is write() function family?
--
An old man doll... just what I always wanted! - Clara
next prev parent reply other threads:[~2022-10-06 2:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-05 10:47 [PATCH v2] locking/memory-barriers.txt: Improve documentation for writel() example Parav Pandit
2022-10-06 2:00 ` Bagas Sanjaya [this message]
2022-10-06 2:40 ` Parav Pandit
2022-10-06 2:48 ` Akira Yokosawa
2022-10-06 2:52 ` Akira Yokosawa
2022-10-06 3:25 ` Parav Pandit
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