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From: "Jakub Kiciński" <moorray3@wp.pl>
To: Peter Oh <poh@qca.qualcomm.com>
Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org
Subject: Re: [PATCH v2] ath10k: Replace ioread with mb to drain write buffer
Date: Fri, 6 Feb 2015 09:58:46 +0100	[thread overview]
Message-ID: <20150206095846.5d46f11e@north> (raw)
In-Reply-To: <7a87e5df81499e4d26a4f8bedf76ed3250a6f7bb.1422663244.git.poh@qca.qualcomm.com>

On Fri, 30 Jan 2015 16:14:30 -0800, Peter Oh wrote:
> Using ioread() to perform draining write buffer is excessive.
> Use compact API, mb(), that intended to be used for the case.
> It reduces total 14 CPU clocks per interrupt.
>
> Signed-off-by: Peter Oh <poh@qca.qualcomm.com>

I have no idea what the code does but this change looks suspicious. 
Usually the point of ioread() is to flush the interconnect buffers 
while mb() ensures ordering only from the CPU perspective.

Could you provide the reason *why* flushing buffers is unnecessary
in the commit message?

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WARNING: multiple messages have this Message-ID (diff)
From: "Jakub Kiciński" <moorray3@wp.pl>
To: Peter Oh <poh@qca.qualcomm.com>
Cc: <ath10k@lists.infradead.org>, <linux-wireless@vger.kernel.org>
Subject: Re: [PATCH v2] ath10k: Replace ioread with mb to drain write buffer
Date: Fri, 6 Feb 2015 09:58:46 +0100	[thread overview]
Message-ID: <20150206095846.5d46f11e@north> (raw)
In-Reply-To: <7a87e5df81499e4d26a4f8bedf76ed3250a6f7bb.1422663244.git.poh@qca.qualcomm.com>

On Fri, 30 Jan 2015 16:14:30 -0800, Peter Oh wrote:
> Using ioread() to perform draining write buffer is excessive.
> Use compact API, mb(), that intended to be used for the case.
> It reduces total 14 CPU clocks per interrupt.
>
> Signed-off-by: Peter Oh <poh@qca.qualcomm.com>

I have no idea what the code does but this change looks suspicious. 
Usually the point of ioread() is to flush the interconnect buffers 
while mb() ensures ordering only from the CPU perspective.

Could you provide the reason *why* flushing buffers is unnecessary
in the commit message?

  parent reply	other threads:[~2015-02-06  8:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-31  0:14 [PATCH v2] ath10k: Replace ioread with mb to drain write buffer Peter Oh
2015-01-31  0:14 ` Peter Oh
2015-01-31  0:22 ` Peter Oh
2015-02-06  8:58 ` Jakub Kiciński [this message]
2015-02-06  8:58   ` Jakub Kiciński
2015-02-06 14:53   ` Jakub Kiciński
2015-02-06 14:53     ` Jakub Kiciński

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