Return-path: Received: from mx3.wp.pl ([212.77.101.10]:51314 "EHLO mx3.wp.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754740AbbBFOxs convert rfc822-to-8bit (ORCPT ); Fri, 6 Feb 2015 09:53:48 -0500 Date: Fri, 6 Feb 2015 15:53:43 +0100 From: Jakub =?UTF-8?B?S2ljacWEc2tp?= To: Peter Oh Cc: , Subject: Re: [PATCH v2] ath10k: Replace ioread with mb to drain write buffer Message-ID: <20150206155343.5fe43aa9@north> (sfid-20150206_155403_514091_2C8F5A71) In-Reply-To: <20150206095846.5d46f11e@north> References: <7a87e5df81499e4d26a4f8bedf76ed3250a6f7bb.1422663244.git.poh@qca.qualcomm.com> <20150206095846.5d46f11e@north> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, 6 Feb 2015 09:58:46 +0100, Jakub Kiciński wrote: > 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 > > 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? I just noticed the discussion on the first version of the patch. Sorry about the noise.