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SubjectRe: [PATCH] cpufreq: respect the min/max settings from user space
Hi Viresh,

Could you remind me where can I find this patch upstream? It seems this
was missed?

Thanks,
Vince

On 10/06/2014 12:50 PM, Vince Hsu wrote:
> Hi Viresh,
>
> On 10/06/2014 12:45 PM, Viresh Kumar wrote:
>> On 2 October 2014 12:25, Vince Hsu <vinceh@nvidia.com> wrote:
>>> When the user space tries to set scaling_(max|min)_freq through
>>> sysfs, the cpufreq_set_policy() asks other driver's opinions
>>> for the max/min frequencies. Some device drivers, like Tegra
>>> CPU EDP which is not upstreamed yet though, may constrain the
>>> CPU maximum frequency dynamically because of board design.
>>> So if the user space access happens and some driver is capping
>>> the cpu frequency at the same time, the user_policy->(max|min)
>>> is overridden by the capped value, and that's not expected by
>>> the user space. And if the user space is not invoked again,
>>> the CPU will always be capped by the user_policy->(max|min)
>>> even no drivers limit the CPU frequency any more.
>>>
>>> This patch preserves the user specified min/max settings, so that
>>> every time the cpufreq policy is updated, the new max/min can
>>> be re-evaluated correctly based on the user's expection and
>>> the present device drivers' status.
>>>
>>> Signed-off-by: Vince Hsu <vinceh@nvidia.com>
>>> ---
>>> Hi,
>>>
>>> I'm not sure if any platform that is supported mainlin might have this
>>> issue, and this patch is complie tested only.
>> Why only compiled tested? Why haven't you tested it on tegra?
> I did test with Chrome kernel on Tegra platform. I can't do that with
> mainline kernel because we haven't had the CPU EDP driver upstream yet.
>
> Thanks,
> Vince
>
>>
>>> drivers/cpufreq/cpufreq.c | 6 ++++--
>>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>>> index 24bf76fba141..c007cf2a3d2a 100644
>>> --- a/drivers/cpufreq/cpufreq.c
>>> +++ b/drivers/cpufreq/cpufreq.c
>>> @@ -524,7 +524,7 @@ static int cpufreq_set_policy(struct
>>> cpufreq_policy *policy,
>>> static ssize_t
>>> store_##file_name \
>>> (struct cpufreq_policy *policy, const char *buf, size_t
>>> count) \
>>> { \
>>> - int
>>> ret; \
>>> + int ret, temp; \
>>> struct cpufreq_policy
>>> new_policy; \
>>> \
>>> ret = cpufreq_get_policy(&new_policy,
>>> policy->cpu); \
>>> @@ -535,8 +535,10 @@ static ssize_t
>>> store_##file_name \
>>> if (ret !=
>>> 1) \
>>> return
>>> -EINVAL; \
>>> \
>>> + temp =
>>> new_policy.object; \
>>> ret = cpufreq_set_policy(policy, &new_policy); \
>>> - policy->user_policy.object =
>>> policy->object; \
>>> + if
>>> (!ret) \
>>> + policy->user_policy.object =
>>> temp; \
>>> \
>>> return ret ? ret :
>>> count; \
>>> }
>> Looks fine otherwise.
>>
>> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
>
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