Part Number:OMAP-L138
Tool/software: Linux
Hi,
I'm working on an OMAP-L138 processor, and the ARM core runs Linux 3.2, whereas the DSP core is baremetal. I need to modify the PLLC registers so that both cores will run at 456 MHz instead of the default setting of 300 MHz.
Referring to the technical reference guide, I have a DSP code that modifies the PLLM, PREDIV, POSTDIV, ... registers. I can confirm the registers are written properly by printing their values after the modification. I was also able to measure the 456 MHz clock from the CLKOUT pin with a spectrum analyzer before. (Note that my voltage value also supports 456 MHz.)
After changing the clock frequency, I boot Linux on ARM; however, once Linux is booted, I see the default values on PLLC registers (which indicate the core is running at 300 MHz). Likewise, cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq also returns 300000 (kHz).
How can I prevent Linux from overriding my PLLC preferences? Do I need to configure the kernel or modify the file system to that end?
Thanks in advance,
Silacko