From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gabriele Mazzotta Subject: Re: [PATCH] Revert "cpufreq: intel_pstate: Fix ->set_policy() interface for no_turbo" Date: Sat, 4 Aug 2018 19:31:50 +0200 Message-ID: References: <20180804152932.3861-1-gabriele.mzt@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180804152932.3861-1-gabriele.mzt@gmail.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: srinivas.pandruvada@linux.intel.com, rjw@rjwysocki.net Cc: lenb@kernel.org, viresh.kumar@linaro.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-pm@vger.kernel.org On 04/08/2018 17:29, Gabriele Mazzotta wrote: > This change does not take into account that some BIOSes change > MSR_IA32_MISC_ENABLE_TURBO_DISABLE depending on the power source. > If the turbo is disabled when the system boots, policy.max_freq > is set to pstate.max_pstate. However, if the BIOS later enables > the turbo, the CPU will never be able to run at pstate.turbo_pstate. > > Since now intel_pstate_set_policy() does its calculations using > pstate.max_freq and pstate.turbo_freq, we can always calculate > cpuinfo.max_freq using pstate.turbo_pstate, thus allowing system > with varying MSR_IA32_MISC_ENABLE_TURBO_DISABLE to run at full > speed when the turbo is enabled. > > This reverts commit 983e600e88835f0321d1a0ea06f52d48b7b5a544. > > Signed-off-by: Gabriele Mazzotta > --- > drivers/cpufreq/intel_pstate.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index 3c3971256130..4043aae2d611 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -2068,9 +2068,8 @@ static int __intel_pstate_cpu_init(struct cpufreq_policy *policy) > /* cpuinfo and default policy values */ > policy->cpuinfo.min_freq = cpu->pstate.min_pstate * cpu->pstate.scaling; > update_turbo_state(); Commit 983e600e8883 added this update_turbo_state() call, but it is needed by intel_pstate_init_acpi_perf_limits() here below. I should have mentioned it in the commit message. However, I've just realized that a similar problem to that I'm trying to fix can occur on those systems where core_frequency is adjusted depending on the availability of the turbo. The call to update_turbo_state() could also be moved in intel_pstate_init_acpi_perf_limits(), right before the check on global.turbo_disabled. > - policy->cpuinfo.max_freq = global.turbo_disabled ? > - cpu->pstate.max_pstate : cpu->pstate.turbo_pstate; > - policy->cpuinfo.max_freq *= cpu->pstate.scaling; > + policy->cpuinfo.max_freq = > + cpu->pstate.turbo_pstate * cpu->pstate.scaling; > > intel_pstate_init_acpi_perf_limits(policy); > >