netdev - Re: [PATCH net-next 11/12] bnxt_en: Expose threshold temperatures through hwmon

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Message-ID: <3d70325b-6b6a-482f-8745-36aceb6b2818@roeck-us.net>
Date: Wed, 16 Aug 2023 05:13:55 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Kalesh Anakkur Purayil <kalesh-anakkur.purayil@...adcom.com>
Cc: Michael Chan <michael.chan@...adcom.com>, davem@...emloft.net,
	netdev@...r.kernel.org, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, gospo@...adcom.com,
	Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH net-next 11/12] bnxt_en: Expose threshold temperatures
 through hwmon

On Wed, Aug 16, 2023 at 03:58:34PM +0530, Kalesh Anakkur Purayil wrote:
> Thank you Guenter for the review and the suggestions.
> 
> Please see my response inline.
> 
> On Tue, Aug 15, 2023 at 8:35 PM Guenter Roeck <linux@...ck-us.net> wrote:
> 
[ ... ]

> >
> > Hmm, that isn't really the purpose of alarm attributes. The expectation
> > would be that the chip sets alarm flags and the driver reports it.
> > I guess there is some value in having it, so I won't object.
> >
> > Anyway, the ordering is wrong. max_alarm should be the lowest
> > alarm level, followed by crit and emergency. So
> >                 max_alarm -> temp >= bp->warn_thresh_temp
> >                 crit_alarm -> temp >= bp->crit_thresh_temp
> >                 emergency_alarm -> temp >= bp->fatal_thresh_temp
> >                                 or temp >= bp->shutdown_thresh_temp
> >
> > There are only three levels of upper temperature alarms.
> > Abusing lcrit as 4th upper alarm is most definitely wrong.
> >
> [Kalesh]: Thank you for the clarification.
> bnxt_en driver wants to expose 4 threshold temperatures to the user through
> hwmon sysfs.
> 1. warning threshold temperature
> 2. critical threshold temperature
> 3. fatal threshold temperature
> 4. shutdown threshold temperature
> 
> I will use the following mapping:
> 
> hwmon_temp_max : warning threshold temperature
> hwmon_temp_crit : critical threshold temperature
> hwmon_temp_emergency : fatal threshold temperature
> 
> hwmon_temp_max_alarm : temp >= bp->warn_thresh_temp
> hwmon_temp_crit_alarm : temp >= bp->crit_thresh_temp
> hwmon_temp_emergency_alarm : temp >= bp->fatal_thresh_temp
> 
> Is it OK to map the shutdown threshold temperature to "hwmon_temp_fault"?

That is a flag, not a temperature, and it is intended to signal
a problem ith the sensor.

> If not, can you please suggest an alternative?
> 

The only one I can think of is to add non-standard attributes
such as temp1_shutdown and temp1_shutdown_alarm.

Guenter