Messages in this thread Patch in this message | | | From | TungChen Shih <> | Subject | [PATCH v2 1/1] cpufreq: fix the target freq not in the range of policy->min & max | Date | Sun, 27 Jun 2021 00:23:25 +0800 |
| |
The function cpufreq_driver_resolve_freq() should return the lowest 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
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--; + } + policy->cached_resolved_idx = idx; return policy->freq_table[idx].frequency; } -- 2.18.0
| |