Messages in this thread | | | Date | Tue, 29 Jun 2021 11:47:58 +0530 | From | Viresh Kumar <> | Subject | Re: [PATCH v2 1/1] cpufreq: fix the target freq not in the range of policy->min & max |
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On 27-06-21, 00:23, TungChen Shih wrote: > The function cpufreq_driver_resolve_freq() should return the lowest
Don't add extra spaces at the beginning of paragraphs here.
> supported freq greater than or equal to the given target_freq, subject > to policy (min/max) and driver limitations. However, the index returned > by cpufreq_frequency_table_target() won't subject to policy min/max in > some cases. > > In cpufreq_frequency_table_target(), this function will try to find > an index for @target_freq in freq_table, and the frequency of selected > index should be in the range [policy->min, policy->max], which means: > > policy->min <= policy->freq_table[idx].frequency <= policy->max > > Though "clamp_val(target_freq, policy->min, policy->max);" would > have been called to check this condition, when policy->max or min is > not exactly one of the frequency in the frequency table, > policy->freq_table[idx].frequency may still go out of the range > > For example, if our sorted freq_table is [3000, 2000, 1000], and > suppose we have: > > @target_freq = 2500 > @policy->min = 2000 > @policy->max = 2200 > @relation = CPUFREQ_RELATION_L > > 1. After clamp_val(target_freq, policy->min, policy->max); @target_freq > becomes 2200 > 2. Since we use CPUFREQ_REALTION_L, final selected freq will be 3000 which > beyonds policy->max
Right so the problem does exist, and not only with cpufreq_driver_resolve_freq(), but __cpufreq_driver_target() as well. I have a sent a patchset to update both of these to start sharing some code and we need to fix this for both now.
> Signed-off-by: TungChen Shih <tung-chen.shih@mediatek.com> > --- > drivers/cpufreq/cpufreq.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 802abc925b2a..8e3a17781618 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -544,8 +544,23 @@ unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy, > if (cpufreq_driver->target_index) { > unsigned int idx; > > + /* to find the frequency >= target_freq */ > idx = cpufreq_frequency_table_target(policy, target_freq, > CPUFREQ_RELATION_L); > + > + /* frequency should subject to policy (min/max) */ > + if (policy->freq_table[idx].frequency > policy->max) { > + if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING) > + idx--; > + else > + idx++; > + } else if (policy->freq_table[idx].frequency < policy->min) { > + if (policy->freq_table_sorted == CPUFREQ_TABLE_SORTED_ASCENDING) > + idx++; > + else > + idx--; > + }
This doesn't look clean to be honest.
Rafael, does it make sense to update cpufreq_frequency_table_target() (and its internal routines) to take policy bounds in consideration, or something else ?
-- viresh
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