i.MX ProcessorsのトピックRe: How to configure fix CPU frequency?

How to configure fix CPU frequency?

matter — Wed, 27 Sep 2017 06:40:26 GMT

Hi,

we use the following development setup:

Processor: IMX6ULL

Board: MCIMX6ULL-14X14-EVK

BSP: git://git.freescale.com/imx/fsl-arm-yocto-bsp.git -b imx-4.1-krogoth

Use case: For efficiency and testing reasons, we want the IMX6ULL processor to always run at the minimum frequency available (198Mhz) - independent of the current system load. Therefore, we want to build a Yocto-based Linux image that ties the processor to that fixed, predefined frequency value. In general, what would be the right/intended way to do this?

So far, we tried to change the kernel configuration by setting the default governor to userspace. Therefore, we followed the steps from the Yocto Manual. However, neither our defconfig nor our config fragments have been recognized by the bitbake build process.

Thanks in advance!

Regards,

Matthias

Re: How to configure fix CPU frequency?

Rita_Wang — Fri, 29 Sep 2017 02:52:35 GMT

if you are running Linux , you can add boot command in the uboot to set it run on the frequency you need .

Please add this in the bootargs.

"arm_freq=***"

Re: How to configure fix CPU frequency?

matter — Fri, 29 Sep 2017 06:36:47 GMT

Ok, but this changes the frequency only while the Linux kernel is loaded, right? Subsequently, the Linux governors (default is ondemand) take over which may change the frequency again.

For this reason, we would like to set the default governor to userspace and set the frequency to a fixed value of 198MHz at compile time using the Yocto build process. How can we achive this?

Regards,

Matthias