AM3352: Changing MPU frequency in U-boot

O.H

Part Number: AM3352

Hi experts,

My customer wants to change the MPU frequency during a U-boot using ti-processor-sdk-linux-am335x-evm-06.03.00.106.

Q1: Unable to find the "do_ setup_dpll" function in "board.c". Has the content changed in version 06.03.00.106?
The following thread indicates that "u-boot-2019.01~~/board/ti/am335x/board.c" should be changed:. However, the "do_setup_dpll" function was not found.
https://e2e.ti.com/support/processors/f/791/t/641050

Q2: Has "u-boot-2016.05/arch/arm/cpu/armv7/am33xx" been changed to "u-boot-2019.01~~/arch/arm/mach-omap2/am33xx"?
The following thread indicates that "board.c" and "clock.c" should be changed. But I can't find "/arch/arm/cpu/armv7/am33xx".
e2e.ti.com/.../2093803

Q3: Is it correct that the MPU frequency can be changed by changing the "do_setup_dpll" function of "u-boot-2019.01~~/arch/arm/mach-omap2/am335xx/clock.c"?

Best Regards,
O.H

over 5 years ago

0 Andreas Dannenberg over 5 years ago

TI__Guru 69602 points

O.H.,

on ti-u-boot-2019.01 based branches you set/change the AM335x CPU frequency by implementing a custom get_dpll_mpu_params() function in your board file, like this here: https://git.ti.com/cgit/processor-sdk/processor-sdk-u-boot/tree/board/ti/am335x/board.c?h=processor-sdk-u-boot-2019.01#n292 This function will then get invoked by the architectural framework (which you should not modify!) setup_dplls() routine located at https://git.ti.com/cgit/processor-sdk/processor-sdk-u-boot/tree/arch/arm/mach-omap2/am33xx/clock.c?h=processor-sdk-u-boot-2019.01#n107.

It can be challenging to forward-port U-Boot customizations, often it is easier to instead start from scratch by adding support for a custom board on top of a new U-Boot release. We now also have a board-porting how-to guide that should hopefully make this process a little easier: https://software-dl.ti.com/processor-sdk-linux/esd/docs/06_03_00_106/AM335X/linux/How_to_Guides_Board_Port.html

Regards, Andreas

0 O.H over 5 years ago in reply to Andreas Dannenberg

Mastermind 6280 points

Hi Andreas,

Thank you for your reply.
Also, it was helpful that you gave me an answer in the latest environment!!
I overlooked the contents of "Developer's Guide"...

Best Regards,
O.H

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AM3352: Changing MPU frequency in U-boot