Re: [PATCH v2] hwmon: Driver for temperature sensors on SATA drives

[Guenter Roeck]

On 1/12/20 10:37 AM, Gabriel C wrote:
> Am So., 12. Jan. 2020 um 16:26 Uhr schrieb Guenter Roeck <linux@xxxxxxxxxxxx>:
> > On 1/12/20 5:45 AM, Gabriel C wrote:
> > > Am So., 12. Jan. 2020 um 14:07 Uhr schrieb Guenter Roeck <linux@xxxxxxxxxxxx>:
> > > > On 1/12/20 4:07 AM, Linus Walleij wrote:
> > > > > On Sun, Jan 12, 2020 at 1:03 PM Gabriel C <nix.or.die@xxxxxxxxx> wrote:
> > > > > > Am So., 12. Jan. 2020 um 12:22 Uhr schrieb Linus Walleij
> > > > > > <linus.walleij@xxxxxxxxxx>:
> > > > > > > On Sun, Jan 12, 2020 at 12:18 PM Gabriel C <nix.or.die@xxxxxxxxx> wrote:
> > > > > > >
> > > > > > > > What I've noticed however is the nvme temperature low/high values on
> > > > > > > > the Sensors X are strange here.
> > > > > > > (...)
> > > > > > > > Sensor 1:     +27.9ÂC  (low  = -273.1ÂC, high = +65261.8ÂC)
> > > > > > > > Sensor 2:     +29.9ÂC  (low  = -273.1ÂC, high = +65261.8ÂC)
> > > > > > > (...)
> > > > > > > > Sensor 1:     +23.9ÂC  (low  = -273.1ÂC, high = +65261.8ÂC)
> > > > > > > > Sensor 2:     +25.9ÂC  (low  = -273.1ÂC, high = +65261.8ÂC)
> > > > > > >
> > > > > > > That doesn't look strange to me. It seems like reasonable defaults
> > > > > > > from the firmware if either it doesn't really log the min/max temperatures
> > > > > > > or hasn't been through a cycle of updating these yet. Just set both
> > > > > > > to absolute min/max temperatures possible.
> > > > > >
> > > > > > Ok I'll check that.
> > > > > >
> > > > > > Do you mean by setting the temperatures to use a lmsensors config?
> > > > > > Or is there a way to set these with a nvme command?
> > > > >
> > > > > Not that I know of.
> > > > >
> > > > > The min/max are the minumum and maximum temperatures the
> > > > > device has experienced during this power-on cycle.
> > > >
> > > > No, that would be lowest/highest. The above are (or should be) per-sensor
> > > > setpoints. The default for those is typically the absolute minimum /
> > > > maximum of the supported range.
> > > >
> > > > Some SATA drives report the lowest/highest temperatures experienced
> > > > since power cycle, like here.
> > > >
> > > > drivetemp-scsi-5-0
> > > > Adapter: SCSI adapter
> > > > temp1:        +23.0ÂC  (low  =  +0.0ÂC, high = +60.0ÂC)
> > > >                           (crit low = -41.0ÂC, crit = +85.0ÂC)
> > > >                           (lowest = +20.0ÂC, highest = +31.0ÂC)
> > >
> > > The SATA temperatures are fine and reported like this here too, just
> > > the nvme ones are strange.
> > >
> > > drivetemp-scsi-4-0
> > > Adapter: SCSI adapter
> > > temp1:        +28.0ÂC  (low  =  +1.0ÂC, high = +61.0ÂC)
> > >                         (crit low =  +2.0ÂC, crit = +60.0ÂC)
> > >                         (lowest = +16.0ÂC, highest = +31.0ÂC)
> > >
> > > drivetemp-scsi-12-0
> > > Adapter: SCSI adapter
> > > temp1:        +29.0ÂC  (low  =  +1.0ÂC, high = +61.0ÂC)
> > >                         (crit low =  +2.0ÂC, crit = +60.0ÂC)
> > >                         (lowest = +18.0ÂC, highest = +32.0ÂC)
> > >
> > > and so on.
> > >
> > > Btw, where I can find the code does these calculations?
> >
> > Not sure if that is what you are looking for, but the nvme hardware
> > monitoring driver is at drivers/nvme/host/hwmon.c, the SATA hardware
> > monitoring driver is at drivers/hwmon/drivetemp.c.
>
> I have a look thanks.
>
> I'm using your v2 patch for the nvme part since you posted it on 5.4 kernels.
> This is probably why I find the way the temperatures are now reported
> very strange.
>
> The ADATA XPG SX8200 Pro in my laptop seems to work better:
>
> nvme-pci-0200
> Adapter: PCI adapter
> Composite:    +37.9ÂC  (low  =  -0.1ÂC, high = +74.8ÂC)
>                        (crit = +79.8ÂC)
>
> Low is 0Â which is what the spec suggests.
>
> > The limits on nvme drives are configurable.
>
> Yes, I found this out already.
>
> > root@server:/sys/class/hwmon# sensors nvme-pci-0100
> > nvme-pci-0100
> > Adapter: PCI adapter
> > Composite:    +40.9ÂC  (low  = -273.1ÂC, high = +84.8ÂC)
> >                          (crit = +84.8ÂC)
> > Sensor 1:     +40.9ÂC  (low  = -273.1ÂC, high = +65261.8ÂC)
> > Sensor 2:     +43.9ÂC  (low  = -273.1ÂC, high = +65261.8ÂC)
> >
> > root@server:/sys/class/hwmon# echo 0 > hwmon1/temp2_min
> > root@server:/sys/class/hwmon# echo 100000 > hwmon1/temp2_max
>
> An lm-sensors configuration will work too.
Sure, the above was just an example.

> > root@server:/sys/class/hwmon# sensors nvme-pci-0100
> > nvme-pci-0100
> > Adapter: PCI adapter
> > Composite:    +38.9ÂC  (low  = -273.1ÂC, high = +84.8ÂC)
> >                          (crit = +84.8ÂC)
> > Sensor 1:     +38.9ÂC  (low  =  -0.1ÂC, high = +99.8ÂC)
> > Sensor 2:     +42.9ÂC  (low  = -273.1ÂC, high = +65261.8ÂC)
> >
> > If you dislike the defaults, just configure whatever you think is
> > appropriate for your system.
>
> It's not about disliking the values. I want to find out if these Samsung models
> don't support that, or it is a bug somewhere in writing/calculating the values.
No, this is not a bug. It is perfectly valid for individual sensors to have
uninitialized limits. If I recall correctly, the NVME specification
specifically states that the default settings for individual sensors
shall be those values (0 and 65535 Kelvin, specifically).

And, yes, I would agree that is a bit odd that NVME drives report temperatures
in Kelvin, but such is the world.

> In the case, Samsung and others don't support such a thing wouldn't be
> better to just ignore
> the bogus reading altogether?

Again, you can set whatever limits you like. The default limits on many
hardware sensor chips have odd values. Just looking at my system:

nct6797-isa-0a20
Adapter: ISA adapter
in0:                    +0.48 V  (min =  +0.00 V, max =  +1.74 V)
in1:                    +1.02 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in2:                    +3.39 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in3:                    +3.31 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in4:                    +1.00 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in5:                    +0.14 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in6:                    +0.82 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in7:                    +3.38 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in8:                    +3.26 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in9:                    +1.82 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in10:                   +0.00 V  (min =  +0.00 V, max =  +0.00 V)
in11:                   +0.74 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in12:                   +1.20 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in13:                   +0.68 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in14:                   +1.50 V  (min =  +0.00 V, max =  +0.00 V)  ALARM


Are you suggesting that we should not support setting min/max values for
all drivers just because they are often not initialized to reasonable values
by default ?

Guenter