From mboxrd@z Thu Jan 1 00:00:00 1970 From: Srinivas Pandruvada Subject: [TEST PATCH] cpufreq: intel_pstate: Workaround to for wrong ACPI perf table entry Date: Tue, 17 Nov 2015 15:00:52 -0800 Message-ID: <1447801252-3626-1-git-send-email-srinivas.pandruvada@linux.intel.com> Return-path: Received: from mga09.intel.com ([134.134.136.24]:2947 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751882AbbKQXCd (ORCPT ); Tue, 17 Nov 2015 18:02:33 -0500 Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: bp@alien8.de, rafael.j.wysocki@intel.com Cc: linux-pm@vger.kernel.org, Srinivas Pandruvada With the implementation of ACPI _PSS and _PPC processing in the Intel P state driver, a bad ACPI configuration can impact max/min states. For example as reported by Borislav Petkov , the log shows: [ 0.826119] intel_pstate: default limits 0xc 0x1d 0x24 [ 0.827000] intel_pstate: CPU0 - ACPI _PSS perf data [ 0.827020] *P0: 2901 MHz, 35000 mW, 0xff00 The above control value of 0xff00, is invalid. The first entry sets the max control value for turbo with a max non turbo frequency + 1 MHz. Here the control values should be 0x1d00. intel_pstate_set_policy() depends on this control value in setting correct max pstate. Two fixes have been done here: - If the control value is invalid then use the physical max turbo as the max. Here 0xff00 will be changed to 0x1d00 - Always reset the limits->min_perf_ctl and limits->max_perf_ctl, so that we will not use last value. In this case even if entry is not found the _PSS it will fallback to limits->max_perf and limits-> limits->max_perf. Reported-by: Borislav Petkov Signed-off-by: Srinivas Pandruvada --- drivers/cpufreq/intel_pstate.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index d3159f0..fc99e97 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -311,6 +311,13 @@ static int intel_pstate_init_perf_limits(struct cpufreq_policy *policy) * correct max turbo frequency based on the turbo ratio. * Also need to convert to MHz as _PSS freq is in MHz. */ + if (turbo_pss_ctl > cpu->pstate.turbo_pstate) { + /* We hava an invalid control value here */ + turbo_pss_ctl = cpu->pstate.turbo_pstate; + cpu->acpi_perf_data.states[0].control = + turbo_pss_ctl << 8; + } + cpu->acpi_perf_data.states[0].core_frequency = turbo_pss_ctl * cpu->pstate.scaling / 1000; } @@ -1272,6 +1279,8 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) #if IS_ENABLED(CONFIG_ACPI) cpu = all_cpu_data[policy->cpu]; + limits->min_perf_ctl = 0; + limits->max_perf_ctl = 0; for (i = 0; i < cpu->acpi_perf_data.state_count; i++) { int control; -- 2.4.3