From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v2 2/2] ARM: perf: Add support for Scorpion PMUs Date: Fri, 27 Feb 2015 19:46:56 +0000 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 Return-path: 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 Content-Disposition: inline In-Reply-To: <54F0C72B.2090501@codeaurora.org> Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org 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" 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 27 Feb 2015 19:46:56 +0000 Subject: [PATCH v2 2/2] ARM: perf: Add support for Scorpion PMUs In-Reply-To: <54F0C72B.2090501@codeaurora.org> 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> Message-ID: <20150227194656.GB24818@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.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