autodetection of maximum AM335x CPU frequency?

Stan Hu

Other Parts Discussed in Thread: AM3352

Is there a way to autodetect the maximum CPU frequency supported by a given AM335x? I have a 250 MHz AM3352, and the Device ID and DEV_FEATURE registers don't seem to have this information. I assume this is because the maximum speed isn't determined until after the manufacturing step, but I would hope that information can be retrieved by some other means.

I can set the CPU frequency using the /sys/devices/system/cpu/cpu0/cpufreq, but I really want to autodetect the maximum frequency either in the bootloader or Linux kernel automatically.

over 13 years ago

0 Greg Guyotte over 13 years ago

TI__Intellectual 1585 points

Stan,

You can dump the list of available frequencies supported by AM335x with:
cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies

The highest number that you see in string that is returned will be the maximum frequency supported.

0 Stan Hu over 13 years ago in reply to Greg Guyotte

Prodigy 130 points

I don't think this list is generated dynamically based on what's actually available on the processor. I have a AM3352ZCZ60, which should be a 600 MHz processor. If I do:

root@spot:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
275000 500000 600000 720000

It shows that 720 is available.

0 Renjith Thomas over 12 years ago in reply to Stan Hu

Guru 31670 points

Stan,

Its set in the list of OPP in the kernel clock manager driver. You'll be able to find this in arch/arm/mach-omap2/clock-xxxx.c file.

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autodetection of maximum AM335x CPU frequency?