* [PATCH v1 1/1] cpufreq: fix the target freq not in the range of policy->min & max
@ 2021-06-25 13:41 TungChen Shih
2021-06-25 14:13 ` Rafael J. Wysocki
0 siblings, 1 reply; 2+ messages in thread
From: TungChen Shih @ 2021-06-25 13:41 UTC (permalink / raw)
To: rjw, viresh.kumar, matthias.bgg
Cc: wsd_upstream, linux-pm, linux-kernel, linux-arm-kernel,
linux-mediatek, TungChen Shih
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>
---
include/linux/cpufreq.h | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 353969c7acd3..60cb15740fdf 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -975,21 +975,40 @@ static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
+ int idx = 0;
if (unlikely(policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED))
return cpufreq_table_index_unsorted(policy, target_freq,
relation);
switch (relation) {
case CPUFREQ_RELATION_L:
- return cpufreq_table_find_index_l(policy, target_freq);
+ idx = cpufreq_table_find_index_l(policy, target_freq);
+ break;
case CPUFREQ_RELATION_H:
- return cpufreq_table_find_index_h(policy, target_freq);
+ idx = cpufreq_table_find_index_h(policy, target_freq);
+ break;
case CPUFREQ_RELATION_C:
- return cpufreq_table_find_index_c(policy, target_freq);
+ idx = cpufreq_table_find_index_c(policy, target_freq);
+ break;
default:
WARN_ON_ONCE(1);
return 0;
}
+
+ /* target index verification */
+ 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--;
+ }
+
+ return idx;
}
static inline int cpufreq_table_count_valid_entries(const struct cpufreq_policy *policy)
--
2.18.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v1 1/1] cpufreq: fix the target freq not in the range of policy->min & max
2021-06-25 13:41 [PATCH v1 1/1] cpufreq: fix the target freq not in the range of policy->min & max TungChen Shih
@ 2021-06-25 14:13 ` Rafael J. Wysocki
0 siblings, 0 replies; 2+ messages in thread
From: Rafael J. Wysocki @ 2021-06-25 14:13 UTC (permalink / raw)
To: TungChen Shih
Cc: Rafael J. Wysocki, Viresh Kumar, Matthias Brugger, wsd_upstream,
Linux PM, Linux Kernel Mailing List, Linux ARM,
moderated list:ARM/Mediatek SoC...
On Fri, Jun 25, 2021 at 3:41 PM TungChen Shih
<tung-chen.shih@mediatek.com> wrote:
>
> 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
As you accurately observed, the policy limits affect the target, not
the frequency that will be used, and "RELATION_L" means "the closest
frequency equal to or above the target".
You are not fixing a bug here IMO, you're changing the documented behavior.
> Signed-off-by: TungChen Shih <tung-chen.shih@mediatek.com>
> ---
> include/linux/cpufreq.h | 25 ++++++++++++++++++++++---
> 1 file changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 353969c7acd3..60cb15740fdf 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -975,21 +975,40 @@ static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
> unsigned int target_freq,
> unsigned int relation)
> {
> + int idx = 0;
> if (unlikely(policy->freq_table_sorted == CPUFREQ_TABLE_UNSORTED))
> return cpufreq_table_index_unsorted(policy, target_freq,
> relation);
>
> switch (relation) {
> case CPUFREQ_RELATION_L:
> - return cpufreq_table_find_index_l(policy, target_freq);
> + idx = cpufreq_table_find_index_l(policy, target_freq);
> + break;
> case CPUFREQ_RELATION_H:
> - return cpufreq_table_find_index_h(policy, target_freq);
> + idx = cpufreq_table_find_index_h(policy, target_freq);
> + break;
> case CPUFREQ_RELATION_C:
> - return cpufreq_table_find_index_c(policy, target_freq);
> + idx = cpufreq_table_find_index_c(policy, target_freq);
> + break;
> default:
> WARN_ON_ONCE(1);
> return 0;
> }
> +
> + /* target index verification */
> + 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--;
> + }
> +
> + return idx;
> }
>
> static inline int cpufreq_table_count_valid_entries(const struct cpufreq_policy *policy)
> --
> 2.18.0
>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2021-06-25 14:13 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-06-25 13:41 [PATCH v1 1/1] cpufreq: fix the target freq not in the range of policy->min & max TungChen Shih
2021-06-25 14:13 ` Rafael J. Wysocki
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).