From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752875Ab3KSOQk (ORCPT ); Tue, 19 Nov 2013 09:16:40 -0500 Received: from arroyo.ext.ti.com ([192.94.94.40]:51589 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752481Ab3KSOQi (ORCPT ); Tue, 19 Nov 2013 09:16:38 -0500 Message-ID: <528B72C1.5060006@ti.com> Date: Tue, 19 Nov 2013 08:16:33 -0600 From: Nishanth Menon User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Viresh Kumar , Shawn Guo CC: "Rafael J. Wysocki" , "cpufreq@vger.kernel.org" , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , Carlos Hernandez Subject: Re: [PATCH] cpufreq: cpufreq-cpu0: Use a sane boot frequency when booting with a mismatched bootloader configuration References: <1384568535-26611-1-git-send-email-nm@ti.com> <20131116134445.GI11014@S2101-09.ap.freescale.net> <528A27F8.3070402@ti.com> <20131118155753.GU11014@S2101-09.ap.freescale.net> <528A4340.3020508@ti.com> <20131119022133.GB18434@S2101-09.ap.freescale.net> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/18/2013 09:46 PM, Viresh Kumar wrote: > On 19 November 2013 07:51, Shawn Guo wrote: >> No, I did not say that. IMO, when cpufreq-cpu0 sees a mismatch, it has >> no way to know or assume which one is correct and which is incorrect. >> The best thing it can do is to fail out without changing anything about >> running frequency and voltage. > > Not specifically on this patch, but this is what I feel about this issue: > > - As we are discussing on the other thread, there is scope of adding > "unknown" field in tables so that people would know that they were > running out of table freq at some point.. Consider something like userspace governor selection -> the device at boot will probably remain in an unknown/"invalid" configuration till the very first transition attempt. I am less worried about the stats than not following what the hardware description is (as stated by device tree/other forms). I staunchly disagree that at a point of mismatch detection, we just refuse to load up cpufreq governor -even though we know from device tree/other alternative entries what the hardware behavior is supposed to be. To refuse to loadup to a known configuration is considering the "valid configuration" data provided to the driver is wrong - an equivalent(considering the i2c example) is that if i2c driver sees bus configured for 3.4MHz and was asked to use 100KHz, it just refuses to load up! > - This is a common problem for all drivers/platforms and not only > cpufreq-cpu0, so the solution has to be generic and not driver > specific.. So, atleast I don't want to get this patch in at any cost, > unless there is a generic solution present.. > - There are non-dt drivers as well, and so freq table is present > with the kernel and we can't support all frequencies that bootloader > may end up with.. The above two are fair comments -> but that implies that policy->cur population should no longer be the responsibility of cpufreq drivers and be the responsibility of cpufreq core. are we stating we want to move that to cpufreq core? -- Regards, Nishanth Menon