From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932853AbcHNK7E (ORCPT ); Sun, 14 Aug 2016 06:59:04 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51864 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932730AbcHNK7B (ORCPT ); Sun, 14 Aug 2016 06:59:01 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Rafael J. Wysocki" , "Srinivas Pandruvada" Date: Sat, 13 Aug 2016 18:42:51 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 155/305] cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo In-Reply-To: X-SA-Exim-Connect-IP: 92.40.249.202 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.37-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Srinivas Pandruvada commit 983e600e88835f0321d1a0ea06f52d48b7b5a544 upstream. When turbo is disabled, the ->set_policy() interface is broken. For example, when turbo is disabled and cpuinfo.max = 2900000 (full max turbo frequency), setting the limits results in frequency less than the requested one: Set 1000000 KHz results in 0700000 KHz Set 1500000 KHz results in 1100000 KHz Set 2000000 KHz results in 1500000 KHz This is because the limits->max_perf fraction is calculated using the max turbo frequency as the reference, but when the max P-State is capped in intel_pstate_get_min_max(), the reference is not the max turbo P-State. This results in reducing max P-State. One option is to always use max turbo as reference for calculating limits. But this will not be correct. By definition the intel_pstate sysfs limits, shows percentage of available performance. So when BIOS has disabled turbo, the available performance is max non turbo. So the max_perf_pct should still show 100%. Signed-off-by: Srinivas Pandruvada [ rjw : Subject & changelog, rewrite in fewer lines of code ] Signed-off-by: Rafael J. Wysocki [bwh: Backported to 3.16: - limits is a perf_limits structure, not a pointer to it - Adjust context] Signed-off-by: Ben Hutchings --- drivers/cpufreq/intel_pstate.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -877,8 +877,11 @@ static int intel_pstate_cpu_init(struct /* cpuinfo and default policy values */ policy->cpuinfo.min_freq = cpu->pstate.min_pstate * cpu->pstate.scaling; - policy->cpuinfo.max_freq = - cpu->pstate.turbo_pstate * cpu->pstate.scaling; + update_turbo_state(); + policy->cpuinfo.max_freq = limits.turbo_disabled ? + cpu->pstate.max_pstate : cpu->pstate.turbo_pstate; + policy->cpuinfo.max_freq *= cpu->pstate.scaling; + policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; cpumask_set_cpu(policy->cpu, policy->cpus);