P 40 GPU I2C Bus registers for GPU Temperature

Hello,

We want to use the I2C interface to query the P 40 GPU for its’ Temperature. We see the P 40 on our I2C bus at 9F (8 bit address). Is there a manual that refers to the I2C registers for the P 40? I am sure it has many registers. We are only concerned with the Temp as this would allow us to control our Chassis Fans more accurately. We can query the P 40 Temperature In-Band through the PCIe bus using Linux. But we need to use the I2C interface to control our Fans.

Thank you,
Aaron

NVIDIA does not disclosure/publish any features or documentation to ordinary people (only marketing jabbering). So you can try to discover it yourself. Something like (for first GPU on GRID K2 card, seems to be TMP411A@0x4c chip):

# i2cdetect -l
i2c-3	i2c       	NVIDIA i2c adapter 2 at 6:00.0  	I2C adapter
i2c-1	smbus     	SMBus I801 adapter at 0e00      	SMBus adapter
i2c-2	i2c       	NVIDIA i2c adapter 2 at 5:00.0  	I2C adapter
i2c-0	i2c       	mga i2c                         	I2C adapter

# i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- 0c -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- 48 -- 4a -- 4c -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         

# sensors-detect
....
Next adapter: NVIDIA i2c adapter 2 at 5:00.0 (i2c-2)
Do you want to scan it? (yes/NO/selectively): y
Client found at address 0x48
Probing for `National Semiconductor LM75'...                No
Probing for `National Semiconductor LM75A'...               No
Probing for `Dallas Semiconductor DS75'...                  No
Probing for `National Semiconductor LM77'...                No
Probing for `Analog Devices ADT7410/ADT7420'...             No
Probing for `Analog Devices ADT7411'...                     No
Probing for `Maxim MAX6642'...                              No
Probing for `Texas Instruments TMP435'...                   No
Probing for `National Semiconductor LM73'...                No
Probing for `National Semiconductor LM92'...                No
Probing for `National Semiconductor LM76'...                No
Probing for `Maxim MAX6633/MAX6634/MAX6635'...              No
Probing for `NXP/Philips SA56004'...                        No
Probing for `SMSC EMC1023'...                               No
Probing for `SMSC EMC1043'...                               No
Probing for `SMSC EMC1053'...                               No
Probing for `SMSC EMC1063'...                               No
Client found at address 0x4a
Probing for `National Semiconductor LM75'...                No
Probing for `National Semiconductor LM75A'...               No
Probing for `Dallas Semiconductor DS75'...                  No
Probing for `National Semiconductor LM77'...                No
Probing for `Analog Devices ADT7410/ADT7420'...             No
Probing for `Analog Devices ADT7411'...                     No
Probing for `Maxim MAX6642'...                              No
Probing for `Texas Instruments TMP435'...                   No
Probing for `National Semiconductor LM73'...                No
Probing for `National Semiconductor LM92'...                No
Probing for `National Semiconductor LM76'...                No
Probing for `Maxim MAX6633/MAX6634/MAX6635'...              No
Probing for `NXP/Philips SA56004'...                        No
Client found at address 0x4c
Probing for `National Semiconductor LM75'...                No
Probing for `National Semiconductor LM75A'...               No
Probing for `Dallas Semiconductor DS75'...                  No
Probing for `Analog Devices ADT7466'...                     No
Probing for `Andigilog aSC7511'...                          No
Probing for `Analog Devices ADM1021'...                     No
Probing for `Analog Devices ADM1021A/ADM1023'...            No
Probing for `Global Mixed-mode Technology G781'...          No
Probing for `Maxim MAX1617'...                              No
Probing for `Maxim MAX1617A'...                             No
Probing for `Maxim MAX1668'...                              No
Probing for `Maxim MAX1805'...                              No
Probing for `Maxim MAX1989'...                              No
Probing for `Maxim MAX6642'...                              No
Probing for `Maxim MAX6655/MAX6656'...                      No
Probing for `TI THMC10'...                                  No
Probing for `National Semiconductor LM84'...                No
Probing for `Genesys Logic GL523SM'...                      No
Probing for `Onsemi MC1066'...                              No
Probing for `Maxim MAX1618'...                              No
Probing for `Maxim MAX1619'...                              No
Probing for `National Semiconductor LM82/LM83'...           No
Probing for `National Semiconductor LM90'...                No
Probing for `National Semiconductor LM89/LM99'...           No
Probing for `National Semiconductor LM86'...                No
Probing for `Analog Devices ADM1032'...                     No
Probing for `Maxim MAX6654'...                              No
Probing for `Maxim MAX6690'...                              No
Probing for `Maxim MAX6657/MAX6658/MAX6659'...              No
Probing for `Maxim MAX6648/MAX6649/MAX6692'...              No
Probing for `Maxim MAX6680/MAX6681'...                      No
Probing for `Maxim MAX6695/MAX6696'...                      No
Probing for `Winbond W83L771W/G'...                         No
Probing for `Winbond W83L771AWG/ASG'...                     No
Probing for `Texas Instruments TMP400'...                   No
Probing for `Texas Instruments TMP401'...                   No
Probing for `Texas Instruments TMP411A'...                  Success!
    (confidence 8, driver `tmp401')
Probing for `Texas Instruments TMP421'...                   No
Probing for `Texas Instruments TMP422'...                   No
Probing for `Texas Instruments TMP423'...                   No
Probing for `Texas Instruments TMP431'...                   No
Probing for `Texas Instruments TMP432'...                   No
Probing for `Texas Instruments TMP435'...                   No
Probing for `Texas Instruments TMP441'...                   No
Probing for `Texas Instruments TMP442'...                   No
Probing for `Texas Instruments TMP451'...                   No
Probing for `Texas Instruments AMC6821'...                  No
Probing for `National Semiconductor LM95235'...             No
Probing for `National Semiconductor LM95245'...             No
Probing for `National Semiconductor LM63'...                No
Probing for `National Semiconductor LM96163'...             No
Probing for `Fintek F75363SG'...                            No
Probing for `National Semiconductor LM73'...                No
Probing for `Maxim MAX6633/MAX6634/MAX6635'...              No
Probing for `Analog Devices ADT7461'...                     No
Probing for `Analog Devices ADT7461A, ON Semiconductor NCT1008'... No
Probing for `NXP/Philips SA56004'...                        No
Probing for `Analog Devices ADT7481'...                     No
Probing for `Fintek F75383S/M'...                           No
Probing for `SMSC EMC1002'...                               No
Probing for `SMSC EMC1023'...                               No
Probing for `SMSC EMC1033'...                               No
Probing for `SMSC EMC1043'...                               No
Probing for `SMSC EMC1046'...                               No
Probing for `SMSC EMC1053'...                               No
Probing for `SMSC EMC1063'...                               No
Probing for `SMSC EMC1072'...                               No
Probing for `SMSC EMC1073'...                               No
Probing for `SMSC EMC1074'...                               No
Probing for `SMSC EMC1402'...                               No
Probing for `SMSC EMC1403'...                               No
Probing for `SMSC EMC1404'...                               No
Probing for `SMSC EMC1422'...                               No
Probing for `SMSC EMC1423'...                               No
Probing for `SMSC EMC1424'...                               No
....

# modprobe tmp401

# echo tmp401 0x4c > /sys/bus/i2c/devices/i2c-2/new_device 

# grep '' /sys/bus/i2c/devices/i2c-2/2-004c/hwmon/hwmon0/*
name:tmp401
temp1_crit:85000
temp1_crit_alarm:0
temp1_crit_hyst:75000
temp1_input:49500
temp1_max:85000
temp1_max_alarm:0
temp1_min:0
temp1_min_alarm:0
temp2_crit:85000
temp2_crit_alarm:0
temp2_crit_hyst:75000
temp2_fault:1
temp2_input:0
temp2_max:85000
temp2_max_alarm:0
temp2_min:0
temp2_min_alarm:0
update_interval:500

# sensors
tmp401-i2c-2-4c
Adapter: NVIDIA i2c adapter 2 at 5:00.0
temp1:        +49.5°C  (low  =  +0.0°C, high = +85.0°C)
                       (crit = +85.0°C, hyst = +75.0°C)
temp2:          FAULT  (low  =  +0.0°C, high = +85.0°C)
                       (crit = +85.0°C, hyst = +75.0°C)

If you have server-based motherboard the temperature-fan control loop for passive cards should be automatic. Example for my IPMI Supermicro+GRID K2 with fan mode set to optimal speed: