linux-kernel - Re: [PATCH v1] thermal: devfreq_cooling: Fix perf state when calculate dfc res

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Date: Wed, 20 Mar 2024 14:15:54 +0000
From: Lukasz Luba <lukasz.luba@....com>
To: Ye Zhang <ye.zhang@...k-chips.com>
Cc: tao.huang@...k-chips.com, heiko@...ech.de, rui.zhang@...el.com,
 finley.xiao@...k-chips.com, linux-rockchip@...ts.infradead.org,
 linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
 daniel.lezcano@...aro.org, rafael@...nel.org
Subject: Re: [PATCH v1] thermal: devfreq_cooling: Fix perf state when
 calculate dfc res_util

Hi Ye,

On 3/20/24 07:57, Ye Zhang wrote:
> The EM power table is sorted ascending，can't index the table by cooling
> device state，so convert cooling state to performance state by
> dfc->max_state - dfc->capped_state.
> 
> Signed-off-by: Ye Zhang <ye.zhang@...k-chips.com>
> ---
>   drivers/thermal/devfreq_cooling.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
> index 50dec24e967a..8fd7cf1932cd 100644
> --- a/drivers/thermal/devfreq_cooling.c
> +++ b/drivers/thermal/devfreq_cooling.c
> @@ -214,7 +214,7 @@ static int devfreq_cooling_get_requested_power(struct thermal_cooling_device *cd
>   
>   		res = dfc->power_ops->get_real_power(df, power, freq, voltage);
>   		if (!res) {
> -			state = dfc->capped_state;
> +			state = dfc->max_state - dfc->capped_state;
>   
>   			/* Convert EM power into milli-Watts first */
>   			rcu_read_lock();

Thank you for the patch. Good catch! It's under the device driver
callback optional thing: get_real_power().

Please send the v2 with extended explanation about the section
of the code, which is triggered by the get_real_power() presence.
Also, please add the tags, so it can be collected by stable kernel.

Fixes: 615510fe13bd2434610 ("thermal: devfreq_cooling: remove old power 
model and use EM")
Cc: 5.11+ <stable@...r.kernel.org> # 5.11+

BTW, how did you trigger that issue? Do you have such a driver
which provides this get_real_power() callback?

Regards,
Lukasz