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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-12 21:49:33 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-03-13 00:37:16 +0100
commit2ed99e39cb9392312c100d9da591c20641c64d12 (patch)
tree488c4931187506f86ead99c64d3f2cf17d6fc764 /drivers/cpufreq
parentfa389e220254c69ffae0d403eac4146171062d08 (diff)
downloadlinux-2ed99e39cb9392312c100d9da591c20641c64d12.tar.bz2
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@gmail.com> Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com> Cc: 3.13+ <stable@vger.kernel.org> # 3.13+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/cpufreq.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index cf485d928903..199b52b7c3e1 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1129,7 +1129,7 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
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 cpu)
* 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");