On Wednesday, March 12, 2014 03:14:51 PM Patrik Lundquist wrote: > On 12 March 2014 12:42, Patrik Lundquist <patrik.lundquist@xxxxxxxxx> wrote: > > On 12 March 2014 00:07, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote: > >> > >> So Patrik, please test this one (resending, so that it gets to linux-pm): > > > > Will do. Might take a couple of days. > > Come to think of it, there's not much to test besides verifying that > cpufreq_driver->get() isn't called like before (i.e. no need to test > on the server). > > So I inserted pr_err()s and they aren't printed when booting my Intel > Xeon CPU E3-1240 V2 while the intel_pstate driver still is used. > > The patch works for me. Awesome, thanks! Appended again with a proper changelog and tags. Dirk, please let me know if you're fine with it. Rafael --- From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Subject: cpufreq: Skip current frequency initialization for ->setpolicy drivers After commit da60ce9f2fac (cpufreq: call cpufreq_driver->get() after calling ->init()) __cpufreq_add_dev() sometimes fails for CPUs handled by intel_pstate, because that driver may return 0 from its ->get() callback if it has not run long enough to collect enough samples on the given CPU. That didn't happen before commit da60ce9f2fac which added policy->cur initialization to __cpufreq_add_dev() to help reduce code duplication in other cpufreq drivers. However, the code added by commit da60ce9f2fac need not be executed for cpufreq drivers having the ->setpolicy callback defined, because the subsequent invocation of cpufreq_set_policy() will use that callback to initialize the policy anyway and it doesn't need policy->cur to be initialized upfront. The analogous code in cpufreq_update_policy() is also unnecessary for cpufreq drivers having ->setpolicy set and may be skipped for them as well. Since intel_pstate provides ->setpolicy, skipping the upfront policy->cur initialization for cpufreq drivers with that callback set will cover intel_pstate and the problem it's been having after commit da60ce9f2fac will be addressed. Fixes: da60ce9f2fac (cpufreq: call cpufreq_driver->get() after calling ->init()) References: https://bugzilla.kernel.org/show_bug.cgi?id=71931 Reported-and-tested-by: Patrik Lundquist <patrik.lundquist@xxxxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Cc: 3.13+ <stable@xxxxxxxxxxxxxxx> # 3.13+ --- drivers/cpufreq/cpufreq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) Index: linux-pm/drivers/cpufreq/cpufreq.c =================================================================== --- linux-pm.orig/drivers/cpufreq/cpufreq.c +++ linux-pm/drivers/cpufreq/cpufreq.c @@ -1129,7 +1129,7 @@ static int __cpufreq_add_dev(struct devi per_cpu(cpufreq_cpu_data, j) = policy; write_unlock_irqrestore(&cpufreq_driver_lock, flags); - if (cpufreq_driver->get) { + if (cpufreq_driver->get && !cpufreq_driver->setpolicy) { policy->cur = cpufreq_driver->get(policy->cpu); if (!policy->cur) { pr_err("%s: ->get() failed\n", __func__); @@ -2143,7 +2143,7 @@ int cpufreq_update_policy(unsigned int c * BIOS might change freq behind our back * -> ask driver for current freq and notify governors about a change */ - if (cpufreq_driver->get) { + if (cpufreq_driver->get && !cpufreq_driver->setpolicy) { new_policy.cur = cpufreq_driver->get(cpu); if (!policy->cur) { pr_debug("Driver did not initialize current freq"); -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
