OMAPL138B-EP: PLL setting

Nancy Wang

Expert 8210 points

Part Number: OMAPL138B-EP
Other Parts Discussed in Thread: OMAPL138

Hi,

kernel 3.3

How to configure PLL in linux?

over 4 years ago

0 Yordan Kovachev over 4 years ago

TI__Guru**** 161600 points

Hi,

You can check arch/arm/mach-davinci/da850-evm.c and da850.c files (or the related files containing omapl138 or lcdk in their names).

Best Regards,
Yordan

0 Nancy Wang over 4 years ago in reply to Yordan Kovachev

TI__Expert 8210 points

Thanks for reply.

I have looked into this post: https://e2e.ti.com/support/processors/f/791/p/642835/2373256

What's the difference between Uboot and kernel source code about PLL setting?

The customer had found pll definition in da850sdi.h.

#define CONFIG_SYS_DA850_PLL0_PLLM 18 /* PLL0 -> 456 MHz */
#define CONFIG_SYS_DA850_PLL1_PLLM 12 /* PLL1 -> 312 MHz */

He had changed the configuration, but it didn't work when running kernel.

0 Yordan Kovachev over 4 years ago in reply to Nancy Wang

TI__Guru**** 161600 points

In general if u-boot only the necessary settings are done, i.e. just the peripherals you need for booting your board. The kernel might need to enable the additional peripherals used (hence the additional PLL settings if necessary).

They can try enabling the PLLs needed in u-boot and let the kernel use the settings as is.

Best Regards,

Yordan

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OMAPL138B-EP: PLL setting