When driver use the cpufreq_frequency_table_verify() as the
cpufreq_driver->verify's callback. It may cause the policy->max
bigger than the freq_qos's max freq.
Just as follow:
unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_available_frequencies
614400 768000 988000 1228800 1469000 1586000 1690000 1833000 2002000 2093000
unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_max_freq
unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_min_freq
unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_max_freq
2002000
unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_min_freq
2002000
When user set the qos_min and qos_max as the same value, and the value
is not in the freq-table, the above scenario will occur.
This is because in cpufreq_frequency_table_verify() func, when it can not
find the freq in table, it will change the policy->max to be a bigger freq,
as above, because there is no 1.9G in the freq-table, the policy->max would
be set to 2.002G. As a result, the cpufreq_policy->max is bigger than the
user's qos_max. This is unreasonable.
So use a smaller freq when can not find the freq in fre-table, to prevent
the policy->max exceed the qos's max freq.
Signed-off-by: Xuewen Yan <[email protected]>
---
drivers/cpufreq/freq_table.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
index c4d4643b6ca6..1d98b8cf1688 100644
--- a/drivers/cpufreq/freq_table.c
+++ b/drivers/cpufreq/freq_table.c
@@ -70,7 +70,7 @@ int cpufreq_frequency_table_verify(struct cpufreq_policy_data *policy,
struct cpufreq_frequency_table *table)
{
struct cpufreq_frequency_table *pos;
- unsigned int freq, next_larger = ~0;
+ unsigned int freq, prev_smaller = 0;
bool found = false;
pr_debug("request for verification of policy (%u - %u kHz) for cpu %u\n",
@@ -86,12 +86,12 @@ int cpufreq_frequency_table_verify(struct cpufreq_policy_data *policy,
break;
}
- if ((next_larger > freq) && (freq > policy->max))
- next_larger = freq;
+ if ((prev_smaller < freq) && (freq <= policy->max))
+ prev_smaller = freq;
}
if (!found) {
- policy->max = next_larger;
+ policy->max = prev_smaller;
cpufreq_verify_within_cpu_limits(policy);
}
--
2.25.1
On 19-03-24, 16:01, Xuewen Yan wrote:
> When driver use the cpufreq_frequency_table_verify() as the
> cpufreq_driver->verify's callback. It may cause the policy->max
> bigger than the freq_qos's max freq.
>
> Just as follow:
>
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_available_frequencies
> 614400 768000 988000 1228800 1469000 1586000 1690000 1833000 2002000 2093000
>
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_max_freq
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_min_freq
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_max_freq
> 2002000
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_min_freq
> 2002000
>
> When user set the qos_min and qos_max as the same value, and the value
> is not in the freq-table, the above scenario will occur.
>
> This is because in cpufreq_frequency_table_verify() func, when it can not
> find the freq in table, it will change the policy->max to be a bigger freq,
> as above, because there is no 1.9G in the freq-table, the policy->max would
> be set to 2.002G. As a result, the cpufreq_policy->max is bigger than the
> user's qos_max. This is unreasonable.
>
> So use a smaller freq when can not find the freq in fre-table, to prevent
freq-table
> the policy->max exceed the qos's max freq.
>
> Signed-off-by: Xuewen Yan <[email protected]>
> ---
> drivers/cpufreq/freq_table.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
Acked-by: Viresh Kumar <[email protected]>
--
viresh
Hi,
On Mar 19, 2024 at 16:01:53 +0800, Xuewen Yan wrote:
> When driver use the cpufreq_frequency_table_verify() as the
> cpufreq_driver->verify's callback. It may cause the policy->max
> bigger than the freq_qos's max freq.
>
> Just as follow:
>
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_available_frequencies
> 614400 768000 988000 1228800 1469000 1586000 1690000 1833000 2002000 2093000
>
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_max_freq
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_min_freq
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_max_freq
> 2002000
> unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_min_freq
> 2002000
>
> When user set the qos_min and qos_max as the same value, and the value
> is not in the freq-table, the above scenario will occur.
>
> This is because in cpufreq_frequency_table_verify() func, when it can not
> find the freq in table, it will change the policy->max to be a bigger freq,
> as above, because there is no 1.9G in the freq-table, the policy->max would
> be set to 2.002G. As a result, the cpufreq_policy->max is bigger than the
> user's qos_max. This is unreasonable.
That's a good catch! Never thought of this.
>
> So use a smaller freq when can not find the freq in fre-table, to prevent
> the policy->max exceed the qos's max freq.
>
> Signed-off-by: Xuewen Yan <[email protected]>
> ---
> drivers/cpufreq/freq_table.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/cpufreq/freq_table.c b/drivers/cpufreq/freq_table.c
> index c4d4643b6ca6..1d98b8cf1688 100644
> --- a/drivers/cpufreq/freq_table.c
> +++ b/drivers/cpufreq/freq_table.c
> @@ -70,7 +70,7 @@ int cpufreq_frequency_table_verify(struct cpufreq_policy_data *policy,
> struct cpufreq_frequency_table *table)
> {
> struct cpufreq_frequency_table *pos;
> - unsigned int freq, next_larger = ~0;
> + unsigned int freq, prev_smaller = 0;
> bool found = false;
>
> pr_debug("request for verification of policy (%u - %u kHz) for cpu %u\n",
> @@ -86,12 +86,12 @@ int cpufreq_frequency_table_verify(struct cpufreq_policy_data *policy,
> break;
> }
>
> - if ((next_larger > freq) && (freq > policy->max))
> - next_larger = freq;
> + if ((prev_smaller < freq) && (freq <= policy->max))
> + prev_smaller = freq;
> }
>
> if (!found) {
> - policy->max = next_larger;
> + policy->max = prev_smaller;
> cpufreq_verify_within_cpu_limits(policy);
LGTM!
Reviewed-by: Dhruva Gole <[email protected]>
--
Best regards,
Dhruva
On Wed, Mar 20, 2024 at 4:21 AM Viresh Kumar <[email protected]> wrote:
>
> On 19-03-24, 16:01, Xuewen Yan wrote:
> > When driver use the cpufreq_frequency_table_verify() as the
> > cpufreq_driver->verify's callback. It may cause the policy->max
> > bigger than the freq_qos's max freq.
> >
> > Just as follow:
> >
> > unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_available_frequencies
> > 614400 768000 988000 1228800 1469000 1586000 1690000 1833000 2002000 2093000
> >
> > unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_max_freq
> > unisoc:/sys/devices/system/cpu/cpufreq/policy0 # echo 1900000 > scaling_min_freq
> > unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_max_freq
> > 2002000
> > unisoc:/sys/devices/system/cpu/cpufreq/policy0 # cat scaling_min_freq
> > 2002000
> >
> > When user set the qos_min and qos_max as the same value, and the value
> > is not in the freq-table, the above scenario will occur.
> >
> > This is because in cpufreq_frequency_table_verify() func, when it can not
> > find the freq in table, it will change the policy->max to be a bigger freq,
> > as above, because there is no 1.9G in the freq-table, the policy->max would
> > be set to 2.002G. As a result, the cpufreq_policy->max is bigger than the
> > user's qos_max. This is unreasonable.
> >
> > So use a smaller freq when can not find the freq in fre-table, to prevent
>
> freq-table
>
> > the policy->max exceed the qos's max freq.
> >
> > Signed-off-by: Xuewen Yan <[email protected]>
> > ---
> > drivers/cpufreq/freq_table.c | 8 ++++----
> > 1 file changed, 4 insertions(+), 4 deletions(-)
>
> Acked-by: Viresh Kumar <[email protected]>
Applied as 6.10 material, thanks!