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SubjectRe: [PATCH] cpufreq: freq_table: Initialize cpuinfo.max_freq to correct max frequency.
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On 11/15/21 10:59 PM, Viresh Kumar wrote:
> On 15-11-21, 19:23, Steev Klimaszewski wrote:
>> Hi Thara,
>>
>> On 11/15/21 1:50 PM, Thara Gopinath wrote:
>>> cpuinfo.max_freq reflects the maximum supported frequency of cpus in a
>>> cpufreq policy. When cpus support boost frequency and if boost is disabled
>>> during boot up (which is the default), cpuinfo.max_freq does not reflect
>>> boost frequency as the maximum supported frequency till boost is explicitly
>>> enabled via sysfs interface later. This also means that policy reports two
>>> different cpuinfo.max_freq before and after turning on boost. Fix this by
>>> separating out setting of policy->max and cpuinfo.max_freq in
>>> cpufreq_frequency_table_cpuinfo.
>>>
>>> e.g. of the problem. Qualcomm sdm845 supports boost frequency for gold
>>> cluster (cpus 4-7). After boot up (boost disabled),
>>>
>>> 1. cat /sys/devices/system/cpu/cpufreq/policy4/cpuinfo_max_freq 2649600
>>> <- This is wrong because boost frequency is
>>>
>>> 2. echo 1 > /sys/devices/system/cpu/cpufreq/boost <- Enable boost cat
>>> /sys/devices/system/cpu/cpufreq/policy4/cpuinfo_max_freq 2803200 <-
>>> max freq reflects boost freq.
>>>
>>> 3. echo 0 > /sys/devices/system/cpu/cpufreq/boost <- Disable boost cat
>>> /sys/devices/system/cpu/cpufreq/policy4/cpuinfo_max_freq 2803200 <-
>>> Discrepancy with step 1 as in both cases boost is disabled.
>>>
>>> Note that the other way to fix this is to set cpuinfo.max_freq in Soc
>>> cpufreq driver during initialization. Fixing it in
>>> cpufreq_frequency_table_cpuinfo seems more generic solution
>>>
>>> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
>>> ---
>>> drivers/cpufreq/freq_table.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
>>> index 67e56cf638ef..6784f94124df 100644
>>> --- a/drivers/cpufreq/freq_table.c
>>> +++ b/drivers/cpufreq/freq_table.c
>>> @@ -35,11 +35,15 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
>>> struct cpufreq_frequency_table *pos;
>>> unsigned int min_freq = ~0;
>>> unsigned int max_freq = 0;
>>> + unsigned int cpuinfo_max_freq = 0;
>>> unsigned int freq;
>>> cpufreq_for_each_valid_entry(pos, table) {
>>> freq = pos->frequency;
>>> + if (freq > cpuinfo_max_freq)
>>> + cpuinfo_max_freq = freq;
>>> +
>>> if (!cpufreq_boost_enabled()
>>> && (pos->flags & CPUFREQ_BOOST_FREQ))
>>> continue;
>>> @@ -57,8 +61,8 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
>>> * If the driver has set its own cpuinfo.max_freq above max_freq, leave
>>> * it as is.
>>> */
>>> - if (policy->cpuinfo.max_freq < max_freq)
>>> - policy->max = policy->cpuinfo.max_freq = max_freq;
>>> + if (policy->cpuinfo.max_freq < cpuinfo_max_freq)
>>> + policy->cpuinfo.max_freq = cpuinfo_max_freq;
>
> You need to keep the check of policy->max here and update policy->max,
> else you will never run at boost freq. I think this is what Steev
> reported as well ?

Hi Viresh,
policy->max is unconditionally set to max_freq in the line before "if
(policy->cpuinfo.max_freq < max_freq)". So this is not the issue Steev
is reporting.
policy->max = max_freq


>
> So basically something like this:
>
> if (policy->max < max_freq)
> policy->max = max_freq;
>
> if (policy->cpuinfo.max_freq < cpuinfo_max_freq)
> policy->cpuinfo.max_freq = cpuinfo_max_freq;
>

--
Warm Regards
Thara (She/Her/Hers)

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