linux-kernel - Re: [PATCH V2] thermal: power_allocator: Avoid overwriting PID coefficients from setup time

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Message-ID: <62f4258a-6739-4a3b-8fc3-09e04ea55dab@arm.com>
Date: Tue, 6 Feb 2024 12:15:33 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: Di Shen <cindygm567@...il.com>, Di Shen <di.shen@...soc.com>
Cc: rafael@...nel.org, daniel.lezcano@...aro.org, rui.zhang@...el.com,
 linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 xuewen.yan@...soc.com, zhanglyra@...il.com, orsonzhai@...il.com
Subject: Re: [PATCH V2] thermal: power_allocator: Avoid overwriting PID
 coefficients from setup time

Hi Di,

On 2/4/24 02:55, Di Shen wrote:
> Hi Lukasz,
> 
> On Thu, Jan 25, 2024 at 2:24 PM Di Shen <di.shen@...soc.com> wrote:
>>
>> When the PID coefficients k_* are set via sysfs before the IPA
>> algorithm is triggered then the coefficients would be overwritten after
>> IPA throttle() is called. The old configuration values might be
>> different than the new values estimated by the IPA internal algorithm.
>>
>> There might be a time delay when this overwriting happens. It
>> depends on the thermal zone temperature value. The temperature value
>> needs to cross the first trip point value then IPA algorithms start
>> operating. Although, the PID coefficients setup time should not be
>> affected or linked to any later operating phase and values must not be
>> overwritten.
>>
>> This patch initializes params->sustainable_power when the governor
>> binds to thermal zone to avoid overwriting k_*. The basic function won't
>> be affected, as the k_* still can be estimated if the sustainable_power
>> is modified.
>>
>> Signed-off-by: Di Shen <di.shen@...soc.com>
>> ---
>>   drivers/thermal/gov_power_allocator.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/thermal/gov_power_allocator.c b/drivers/thermal/gov_power_allocator.c
>> index 81e061f183ad..1b17dc4c219c 100644
>> --- a/drivers/thermal/gov_power_allocator.c
>> +++ b/drivers/thermal/gov_power_allocator.c
>> @@ -711,6 +711,8 @@ static int power_allocator_bind(struct thermal_zone_device *tz)
>>
>>          if (!tz->tzp->sustainable_power)
>>                  dev_warn(&tz->device, "power_allocator: sustainable_power will be estimated\n");
>> +       else
>> +               params->sustainable_power = tz->tzp->sustainable_power;
>>
>>          estimate_pid_constants(tz, tz->tzp->sustainable_power,
>>                                 params->trip_switch_on,
>> --
>> 2.17.1
>>
> 
> Any comments on patchv2?
> Looking forward to hearing from you. Thanks!

My apologies I was out-of-office.

That v2 patch looks good. Although, please resend it as a new
message, not as a response to the v1. In that way it's easier to
pick it up by maintainers. You can use a tag:
[RESEND][PATCH v2] .....

You can add
Reviewed-by: Lukasz Luba <lukasz.luba@....com>

Regards,
Lukasz