i.MX ProcessorsのトピックHow to chage DDR 352MHz on Kernel

How to chage DDR 352MHz on Kernel

bordonkuo — Sun, 18 Sep 2016 06:53:31 GMT

Dear all

I change the DDR 352MHz based on Android 6.0.1 in imx6dl chip. And I only modify the U-boot. After the system is boot-up, it will change DDR clock on Kernel, right?

But I don't know how to change it ?

Thanks,

Bordon

Re: How to chage DDR 352MHz on Kernel

igorpadykov — Sun, 18 Sep 2016 23:34:48 GMT

Hi Bordon

frequency is changed by cpufreq driver, please refer to description

in attached Linux Manual Chapter 21 Low-level Power Management (PM) Driver,

Chapter 23 CPU Frequency Scaling (CPUFREQ) Driver, Chapter 24

procedure for changing frequency may be found in

linux/arch/arm/mach-imx/ddr3_freq_imx6.S

linux-2.6-imx.git - Freescale i.MX Linux Tree

Best regards
igor
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Re: How to chage DDR 352MHz on Kernel

bordonkuo — Mon, 19 Sep 2016 09:40:35 GMT

Hi,

Could I do not change the DDR clock on Kernel ? Currently I modify the DDR clock on UBoot and look like fine.

When the system boot-up, it will stop on "Starting Kernel..." .

Re: How to chage DDR 352MHz on Kernel

igorpadykov — Mon, 19 Sep 2016 09:49:33 GMT

one can try to change fsl,max_ddr_freq = <528000000>; in imx6q.dtsi :

linux-2.6-imx.git - Freescale i.MX Linux Tree

in general stop on "Starting Kernel..." may mean ddr errors and one

can check ddr with ddr tester

https://community.freescale.com/docs/DOC-105652

Re: How to chage DDR 352MHz on Kernel

bordonkuo — Tue, 20 Sep 2016 02:57:37 GMT

Currently I modify the register (0x020C4018) for 0x000A8324 on Uboot, it is working and no error message. When the system is going to the Kernel, does it initial the DDR again ?

Could I bypass the initial DDR on Kernel ?

Or ....