From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Prakash, Prashanth" Subject: Re: [PATCH 0/2] additional sysfs entries for CPPC Date: Fri, 3 Mar 2017 11:32:55 -0700 Message-ID: <11d1f119-1dac-1045-cd86-14972982bb29@codeaurora.org> References: <1481763994-28146-1-git-send-email-pprakash@codeaurora.org> <72d699cd-06fb-7896-1325-5fc74c4f9888@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:50836 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751803AbdCCSkt (ORCPT ); Fri, 3 Mar 2017 13:40:49 -0500 In-Reply-To: Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" , Al Stone Cc: ACPI Devel Maling List , "Rafael J. Wysocki" , Alexey Klimov , Hoan Tran , Christopher Covington Hi Rafael, On 2/13/2017 9:38 AM, Prakash, Prashanth wrote: [...] >>> Tested-by: Al Stone >> I'm not actually sure about the assumption this series is based on. >> >> I don't see anything in the spec to guarantee that it will always be >> safe to evaluate _CPC only once and cache its output. > Among the Performance capabilities registers(section 8.4.7.1.1), the only > register that can change dynamically is Guaranteed performance register. > We are not supporting/using Guaranteed performance at the moment. > > Guaranteed performance Register has an associated Notify event which will be > invoked when it changes. No such events are associated with other capabilities > register. Similar distinction is made in the beginning of section 8.4.7.1.1: > "Figure 8-47 outlines the static performance thresholds of the platform > and the dynamic guaranteed performance threshold." > > I agree spec isn't very clear about marking these registers as static except > that one sentence I quoted above, but there is enough in spec to guarantee > that the capabilities we are using will not change dynamically. Does the above sound reasonable? Any other feedback on this patch set? -- Thanks, Prashanth