[PATCH v2 1/3] wifi: mt76: mt7915: rework mt7915_thermal_set_cur_throttle_state()

[Nicolas Cavallari]

On 07/12/2022 06:24, Howard Hsu wrote:
> This patch includes 3 changes:
> 1. The maximum throttle state can be set to 100 to fix the problem that
> thermal_protect_disable can never be triggered.

You are modifying the cooling_device part.  The cooling_device is 
explicitly configured to have a max state of MT7915_CDEV_THROTTLE_MAX 
(=99), so the thermal subsystem will probably prevent 
mt7915_thermal_set_cur_throttle_state from being called with a higher 
value.  It will also probably complain if get_cur_state starts returning 
values above MT7915_CDEV_THROTTLE_MAX.

And, as the comment below indicates, the thermal subsystem expect that a 
higher state provide more cooling.  So if 99 means "maximum cooling", 
100 cannot mean "disable cooling".

Also, last time I tried, thermal_protect_disable didn't work; It didn't 
disable anything, the previous thermal throttle kept being applied. 
Maybe a new firmware fixed this, but the kernel cannot simply expect the 
firmware to be up to date.

> 2. Throttle state do not need to be different from the previous state.
> This will make it is impossible for users to just change the
> trigger/restore temp but not the throttle state.

The throttle state is mostly set by the kernel's thermal governor and 
the user has only very little control over it.  The thermal governor 
runs every X seconds and will change the state if it thinks it is too 
low or too high.

The default step_wise governor will aggressively set it to zero if the 
system isn't overheating, for example.

> 3. Add dev_err so that it is easier to see invalid setting while looking at dmesg.
> 
> Fixes: 771cd8d4c369 ("mt76: mt7915e: Fix degraded performance after temporary overheat")
> Co-developed-by: Ryder Lee <ryder.lee at mediatek.com>
> Signed-off-by: Ryder Lee <ryder.lee at mediatek.com>
> Signed-off-by: Howard Hsu <howard-yh.hsu at mediatek.com>
> ---
>   .../net/wireless/mediatek/mt76/mt7915/init.c   | 18 ++++++++++--------
>   1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> index c810c31fbd6e..abeecf15f1c8 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> @@ -131,14 +131,17 @@ mt7915_thermal_set_cur_throttle_state(struct thermal_cooling_device *cdev,
>   	u8 throttling = MT7915_THERMAL_THROTTLE_MAX - state;
>   	int ret;
>   
> -	if (state > MT7915_CDEV_THROTTLE_MAX)
> +	if (state > MT7915_THERMAL_THROTTLE_MAX) {
> +		dev_err(phy->dev->mt76.dev,
> +			"please specify a valid throttling state\n");
>   		return -EINVAL;
> +	}
>   
> -	if (phy->throttle_temp[0] > phy->throttle_temp[1])
> -		return 0;
> -
> -	if (state == phy->cdev_state)
> -		return 0;
> +	if (phy->throttle_temp[0] > phy->throttle_temp[1]) {
> +		dev_err(phy->dev->mt76.dev,
> +			"temp1_crit shall not be greater than temp1_max\n");
> +		return -EINVAL;
> +	}
>   
>   	/*
>   	 * cooling_device convention: 0 = no cooling, more = more cooling
            ^^^^^^^^^^^^^^^^^^^^^^^^^