From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx3.wp.pl ([212.77.101.9]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YJkIQ-0007QD-2E for ath10k@lists.infradead.org; Fri, 06 Feb 2015 14:54:16 +0000 Date: Fri, 6 Feb 2015 15:53:43 +0100 From: Jakub =?UTF-8?B?S2ljacWEc2tp?= Subject: Re: [PATCH v2] ath10k: Replace ioread with mb to drain write buffer Message-ID: <20150206155343.5fe43aa9@north> In-Reply-To: <20150206095846.5d46f11e@north> References: <7a87e5df81499e4d26a4f8bedf76ed3250a6f7bb.1422663244.git.poh@qca.qualcomm.com> <20150206095846.5d46f11e@north> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "ath10k" Errors-To: ath10k-bounces+kvalo=adurom.com@lists.infradead.org To: Peter Oh Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org T24gRnJpLCA2IEZlYiAyMDE1IDA5OjU4OjQ2ICswMTAwLCBKYWt1YiBLaWNpxYRza2kgd3JvdGU6 Cj4gT24gRnJpLCAzMCBKYW4gMjAxNSAxNjoxNDozMCAtMDgwMCwgUGV0ZXIgT2ggd3JvdGU6Cj4g PiBVc2luZyBpb3JlYWQoKSB0byBwZXJmb3JtIGRyYWluaW5nIHdyaXRlIGJ1ZmZlciBpcyBleGNl c3NpdmUuCj4gPiBVc2UgY29tcGFjdCBBUEksIG1iKCksIHRoYXQgaW50ZW5kZWQgdG8gYmUgdXNl ZCBmb3IgdGhlIGNhc2UuCj4gPiBJdCByZWR1Y2VzIHRvdGFsIDE0IENQVSBjbG9ja3MgcGVyIGlu dGVycnVwdC4KPiA+Cj4gPiBTaWduZWQtb2ZmLWJ5OiBQZXRlciBPaCA8cG9oQHFjYS5xdWFsY29t bS5jb20+Cj4gCj4gSSBoYXZlIG5vIGlkZWEgd2hhdCB0aGUgY29kZSBkb2VzIGJ1dCB0aGlzIGNo YW5nZSBsb29rcyBzdXNwaWNpb3VzLiAKPiBVc3VhbGx5IHRoZSBwb2ludCBvZiBpb3JlYWQoKSBp cyB0byBmbHVzaCB0aGUgaW50ZXJjb25uZWN0IGJ1ZmZlcnMgCj4gd2hpbGUgbWIoKSBlbnN1cmVz IG9yZGVyaW5nIG9ubHkgZnJvbSB0aGUgQ1BVIHBlcnNwZWN0aXZlLgo+IAo+IENvdWxkIHlvdSBw cm92aWRlIHRoZSByZWFzb24gKndoeSogZmx1c2hpbmcgYnVmZmVycyBpcyB1bm5lY2Vzc2FyeQo+ IGluIHRoZSBjb21taXQgbWVzc2FnZT8KCkkganVzdCBub3RpY2VkIHRoZSBkaXNjdXNzaW9uIG9u IHRoZSBmaXJzdCB2ZXJzaW9uIG9mIHRoZSBwYXRjaC4KU29ycnkgYWJvdXQgdGhlIG5vaXNlLgoK X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KYXRoMTBrIG1h aWxpbmcgbGlzdAphdGgxMGtAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRwOi8vbGlzdHMuaW5mcmFk ZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2F0aDEwawo= From mboxrd@z Thu Jan 1 00:00:00 1970 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.