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@vger.kernel.org # v5.7+ Reported-by: Thara Gopinath thara.gopinath@linaro.org 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@linaro.org
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@arm.com Tested-by: Lukasz Luba lukasz.luba@arm.com
Regards, Lukasz