Re: [PATCH] nvme: hwmon: Add support for throttling temperature feature

[Tokunori Ikegami <ikegami.t@gmail.com>]

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Hi,

Thanks for your comments.

On 2022/08/06 17:31, Guenter Roeck wrote:
> On Sat, Aug 06, 2022 at 02:46:06PM +0900, Tokunori Ikegami wrote:
>> NVMe drives support host controlled thermal management feature as optional.
>> The thermal management temperature are different from the temperature threshold.
>> So add functionality to set the throttling temperature values.
>>
>> Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>

I think actually the suggested attributes are not met with the 
throttling temperatures as below.

   temp[1-*]_emergency: Temperature emergency max value, for chips 
supporting more than two upper temperature limits.
   temp[1-*]_lcrit: Temperature critical min value, typically lower than 
corresponding temp_min values.

   Thermal Management Temperature 1 (TMT1): This field specifies the 
temperature, in Kelvins, when the controller begins to transition to 
lower power active power states or performs vendor specific thermal 
management actions while minimizing the impact on performance (e.g., 
light throttling) in order to attempt to reduce the Composite Temperature.
   Thermal Management Temperature 2 (TMT2): This field specifies the 
temperature, in Kelvins, when the controller begins to transition to 
lower power active power states or perform vendor specific thermal 
management actions regardless of the impact on performance (e.g., heavy 
throttling) in order to attempt to reduce the Composite Temperature.

> NACK. There are several existing limit attributes which can be used
> for this purpose. I would suggest to use EMERGENCY and LCRIT attributes.
>
> Furthermore, one can not just extend the hwmon ABI without discussion,
> much less as part of a patch introducing its use. Any attribute introduced
> into the ABI must benefit more than one device, and a matching
> implementation in the sensors command and the lm-sensors library is
> expected.

Sorry I am not sure about the hwmon ABI situation but if possible could 
you please consider or discuss to extend the attributes from this patch 
review since the suggested attributes seem difficult to use instead? (Is 
it difficult?)
By the way I have already created the lm-sensors pull request below.
   <https://github.com/lm-sensors/lm-sensors/pull/406>

Regards,
Ikegami

>
> Guenter