Cannot access or change GPU frequency on TX1.

Autonomous Machines Jetson & Embedded Systems Jetson TX1
1

On a custom TX1 board 4.4 kernel:

Running jetson_clocks.sh gives the following output:

Setting clocks to Max using jetson_clocks.sh 
[  354.715487] gk20a 57000000.gpu: railgate is disabled.
/apps/bin/jetson_clocks.sh: line 252: /sys/devices/57000000.gpu/devfreq/57000000.gpu/min_freq: No such file or directory
Error: Failed to max GPU frequency!

Similarly running jetson_clocks --show, gives:

CPU Cluster Switching: Disabled
cpu0: Gonvernor=performance MinFreq=1734000 MaxFreq=1734000 CurrentFreq=1734000
cpu1: Gonvernor=performance MinFreq=1734000 MaxFreq=1734000 CurrentFreq=1734000
cpu2: Gonvernor=performance MinFreq=1734000 MaxFreq=1734000 CurrentFreq=1734000
cpu3: Gonvernor=performance MinFreq=1734000 MaxFreq=1734000 CurrentFreq=1734000
cat: /sys/devices/57000000.gpu/devfreq/57000000.gpu/min_freq: No such file or directory
cat: /sys/devices/57000000.gpu/devfreq/57000000.gpu/max_freq: No such file or directory
cat: /sys/devices/57000000.gpu/devfreq/57000000.gpu/cur_freq: No such file or directory
GPU MinFreq= MaxFreq= CurrentFreq=
EMC MinFreq=12750000 MaxFreq=1600000000 CurrentFreq=1600000000 FreqOverride=1

Looking at
The directory /sys/devices/57000000.gpu doesn’t have a folder called devfreq.

In the bootlog:
[    0.219897] platform 57000000.gpu: domain=ffffffc0fa25e018 allocates as[0]=ffffffc0fa17c318
[    0.219978] platform 57000000.gpu: domain=ffffffc0fa25e018 allocates as[1]=ffffffc0fa17c380
[    0.220055] platform 57000000.gpu: domain=ffffffc0fa25e018 allocates as[2]=ffffffc0fa17c3e8
[    0.220125] platform 57000000.gpu: domain=ffffffc0fa25e018 allocates as[3]=ffffffc0fa17c450
[    0.529612] tegra_gpu_edp gpu_edp: unable to get max GPU freq
[    0.531521] vdd-gpu: applied init 1000000uV constraint
[    0.531555] vdd-gpu: 710 <--> 1320 mV at 1000 mV 
[    2.463286] gk20a 57000000.gpu: platform probe failed

Note I can run GPU code, it just runs very slowly.

Any ideas as to why I am unable to access the Gpu frequencies?

2

Turns out the answer is that that I did not have an option enabled in my kernel config. Fix is to enable this option:

CONFIG_GK20A_DEVFREQ=y