From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753409AbbKCJtu (ORCPT ); Tue, 3 Nov 2015 04:49:50 -0500 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]:42113 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753267AbbKCJtp (ORCPT ); Tue, 3 Nov 2015 04:49:45 -0500 Date: Tue, 3 Nov 2015 17:45:34 +0800 From: Jisheng Zhang To: Arnd Bergmann CC: , Daniel Lezcano , , Subject: Re: [PATCH] clocksource: dw_apb_timer_of: support timer-based delay Message-ID: <20151103174534.2c9f5eeb@xhacker> In-Reply-To: <6198599.NHtefZl19R@wuerfel> References: <1446193659-1698-1-git-send-email-jszhang@marvell.com> <5909853.Bs72yAP0HH@wuerfel> <20151103145940.18ab648f@xhacker> <6198599.NHtefZl19R@wuerfel> X-Mailer: Claws Mail 3.13.0 (GTK+ 2.24.28; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2015-11-03_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=inbound_notspam policy=inbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1507310000 definitions=main-1511030169 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear Arnd On Tue, 3 Nov 2015 09:49:32 +0100 Arnd Bergmann wrote: > On Tuesday 03 November 2015 14:59:40 Jisheng Zhang wrote: > > > On Monday 02 November 2015 11:03:34 Jisheng Zhang wrote: > > > > On Fri, 30 Oct 2015 13:42:01 +0100 Arnd Bergmann wrote: > > > I'd be happier with a solution that keeps the DT describing the hardware > > > and not the way we expect Linux to use it, and instead has some heuristic > > > in the selection of the delay timer. At the moment, we purely base this > > > on the frequency, which as you say is suboptimal. > > > > > > One possible way to improve this would be to add an optional 'latency' > > > property to the DT nodes (or the driver), and use a combination of latency > > > and resolution to make the decision. > > > > Got it. Thanks for the suggestions. The 'latency' here seems a 'rating' > > similar as the one in clocksource. I will cook a series for review: > > > > patch 1 to make register_current_timer_delay() aware of 'rating' > > > > patch 2 to set rating of arch timer as 400 > > > > patch 3 to add timer based delay support to dw_apb_timer whose rating is 300 > > Ok. Just to make sure I got this right: your plan is to use the existing > 'rating' setting as a primary indication, and fall back to comparing the > frequency if the rating is the same? Yes, this is my plan. Thanks, Jisheng