From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755151AbbB0Tq6 (ORCPT ); Fri, 27 Feb 2015 14:46:58 -0500 Received: from foss.arm.com ([217.140.101.70]:44092 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752318AbbB0Tq4 (ORCPT ); Fri, 27 Feb 2015 14:46:56 -0500 Date: Fri, 27 Feb 2015 19:46:56 +0000 From: Will Deacon To: Stephen Boyd Cc: Ashwin Chaugule , "linux-kernel@vger.kernel.org" , "linux-arm-msm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Mark Rutland , Neil Leeder , Ashwin Chaugule , "devicetree@vger.kernel.org" Subject: Re: [PATCH v2 2/2] ARM: perf: Add support for Scorpion PMUs Message-ID: <20150227194656.GB24818@arm.com> References: <1423851849-6069-1-git-send-email-sboyd@codeaurora.org> <1423851849-6069-3-git-send-email-sboyd@codeaurora.org> <20150220193552.GE1767@arm.com> <20150220201627.GD24928@codeaurora.org> <54F0C72B.2090501@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <54F0C72B.2090501@codeaurora.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 27, 2015 at 07:36:11PM +0000, Stephen Boyd wrote: > On 02/25/15 08:58, Ashwin Chaugule wrote: > > Its a count control register (PMxEVCNTCR). Theres various conditions > > on which you can select when to start/stop counting. e.g. start when > > another counter register overflows. Setting it to 0 was the > > recommended default value on Scorpions and Kraits. Reset value is > > unpredictable. So, just need to make sure this is set every time a > > counter is setup. Will that still work if this is moved to the reset > > path? > > I don't think anything in this register changes unless we reset the CPU > or software changes it, right? We already have a hotplug notifier to > handle the case where the CPU is hotplugged out (and may get reset) and > we need to reset the PMU. The other case is deep idle, which we don't > have yet but we'll need to do a save/reset/restore across idle when we > get there. So it seems possible to move it to the PMU reset path. That would be my preference! Please respin the patches and I'll take another look. Will