From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shilpasri G Bhat Subject: Re: [PATCH v2 2/2] cpufreq: powernv: Register for OCC related opal_message notification Date: Tue, 28 Apr 2015 14:37:37 +0530 Message-ID: <553F4DD9.5060509@linux.vnet.ibm.com> References: <1430202214-13807-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <1430202214-13807-3-git-send-email-shilpa.bhat@linux.vnet.ibm.com> <553F426B.3050601@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from e28smtp09.in.ibm.com ([122.248.162.9]:45061 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932510AbbD1JIH (ORCPT ); Tue, 28 Apr 2015 05:08:07 -0400 Received: from /spool/local by e28smtp09.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 28 Apr 2015 14:38:04 +0530 In-Reply-To: Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Viresh Kumar Cc: "linuxppc-dev@ozlabs.org" , Linux Kernel Mailing List , "Rafael J. Wysocki" , Preeti U Murthy , "linux-pm@vger.kernel.org" On 04/28/2015 02:23 PM, Viresh Kumar wrote: > On 28 April 2015 at 13:48, Shilpasri G Bhat > wrote: >> My bad I haven't added explicit comment to state reason behind this change. >> >> I modified the definition of *throttle_check() to match the function definition >> to be called via smp_call() instead of adding an additional wrapper around >> *throttle_check(). >> >> OCC is a chip entity and any local throttle state changes should be associated >> to cpus belonging to that chip. The *throttle_check() will read the core >> register PMSR to verify throttling. All the cores in a chip will have the same >> throttled state as they are managed by a the same OCC in that chip. >> >> smp_call() is required to ensure *throttle_check() is called on a cpu belonging >> to the chip for which we have received throttled/unthrottled notification. We >> could be handling throttled/unthrottled notification of 'chip1' in 'chip2' so do >> an smp_call() on 'chip1'. > > Okay. Lets talk about the code that is already present in mainline. Isn't that > suffering from this issue ? If yes, then you need to bugfix that separately. Nope. The upstream code does not have this issue as it does not have checks to detect unthrottling state. The unthrottling i.e, 'throttled=false' is being handled only in this patchset. Yes this can be fixed separately. > >> We are irq_disabled in powernv_cpufreq_occ_msg() the notification handler. >> Thus the use of kworker to do an smp_call and restore policy->cur. >> >> OCC_RESET is global event it affects frequency of all chips. Pmax capping is >> local event, it affects the frequency of a chip. >> > >>> That's a lot. I am not an expert here and so really can't comment on >>> the internals of ppc. But, is it patch solving a single problem ? I don't >>> know, I somehow got the impression that it can be split into multiple >>> (smaller & review-able) patches. Only if it makes sense. Your call. >> >> All the changes introduced in this patch is centered around opal_message >> notification handler powernv_cpufreq_occ_msg(). I can split it into multiple >> patches but it all will be relevant only to solve the above problem. > > And that's what I meant here. Yes, this all is solving a central problem, but > a patch must be divided into separate, independently working, entities. > Yup agree. Will do.