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VIA SOM-9X50-STK Yocto 3.1 EVK Quick Start Guide
3.4 DVFS
To verify the DVFS (Dynamic Voltage Frequency Scaling) function and list all the supported features, use the
following commands:
root@aiv8385-linux:~# ls –al /sys/devices/system/cpu/cpu0/cpufreq/
total 0
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 affected_cpus
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 cpuinfo_cur_freq
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 cpuinfo_max_freq
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 cpuinfo_min_freq
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 cpuinfo_transition_latency
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 related_cpus
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_available_frequencies
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_available_governors
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_cur_freq
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_driver
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_governor
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_max_freq
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_min_freq
-rwxr-xr-x 1 root root 4096 Dec 31 10:21 scaling_setspeed
drwxr-xr-x 2 root root 0 Dec 31 10:21 stats
To check the supported and current CPU frequency, use the following commands:
:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
1989000 1924000 1846000 1781000 1716000 1677000 1625000 1586000 1508000 1417000 1326000
1248000 1131000 1014000 910000 793000
:~# cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
793000
3.5
Display
The VIA SOM-9X50-STK supports a choice of HDMI and LCD Panel display devices. To set the display device,
first connect the Windows 10 host machine and the VIA SOM-9X50-STK through the Micro USB 2.0 port using a
Micro USB cable.
Then set the two OS image jumpers (J7 and J5) to the download mode.
OS image jumpers diagram
Plug in the AC-to-DC power adapter to power on the VIA SOM-9X50-STK.
Use the following command to enter the Fastboot Mode.
root@aiv8385-linux:~# reboot bootloader
Make sure there is a "fastboot: processing commands" message in the debug console.
Next, run the cmd.exe on your Windows 10 host machine.
