Hi Viresh,
On 2/17/21 5:48 AM, Viresh Kumar wrote:
freq_qos_update_request() returns 1 if the effective constraint value
has changed, 0 if the effective constraint value has not changed, or a
negative error code on failures.
The frequency constraints for CPUs can be set by different parts of the
kernel. If the maximum frequency constraint set by other parts of the
kernel are set at a lower value than the one corresponding to cooling
state 0, then we will never be able to cool down the system as
freq_qos_update_request() will keep on returning 0 and we will skip
updating cpufreq_state and thermal pressure.
To be precised, thermal pressure signal is not so important in this
mechanism and the 'cpufreq_state' has changed recently:
236761f19a4f373354 thermal/drivers/cpufreq_cooling: Update
cpufreq_state only if state has changed
Fix that by doing the updates even in the case where
freq_qos_update_request() returns 0, as we have effectively set the
constraint to a new value even if the consolidated value of the
actual constraint is unchanged because of external factors.
Cc: v5.7+ <stable@xxxxxxxxxxxxxxx> # v5.7+
Reported-by: Thara Gopinath <thara.gopinath@xxxxxxxxxx>
Fixes: f12e4f66ab6a ("thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping")
I'm not sure if that f12e4f is the root cause.
Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
---
Hi Guys,
This needs to go in 5.12-rc.
Thara, please give this a try and give your tested-by :).
drivers/thermal/cpufreq_cooling.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Anyway, the fix LGTM. I will have to make sure that I'm CC'ed for these
topic, so I can have a look (I missed somehow 236761f19)
Reviewed-by: Lukasz Luba <lukasz.luba@xxxxxxx>
Tested-by: Lukasz Luba <lukasz.luba@xxxxxxx>
Regards,
Lukasz
