Re: [PATCH] cpufreq: freq_table: Initialize cpuinfo.max_freq to correct max frequency.

[Thara Gopinath]

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@xxxxxxxxxx>
> > > ---
> > >    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)