How to change DDR frequency in imx8mq

[kinjalGediya]

Hello NXP,

we are using imx8mq processor for development, so here are few quries for DDR.
1. How can we check DDR frequency at userspace?
2. How can we change DDR frequncy at runtime?

Hope for your quick reply.

Thanks,

[nxf63675]

Hi @kinjalGediya,

Q1: You can do this by following this post,

https://www.cyberciti.biz/faq/check-ram-speed-linux/

Q2: I thing that at runtime is not possible to change the DDR speed, but if you still one to do it algorithms describing change of DDR frequency are provided in sect.2.3.4 Dynamic Bus Frequency Linux Manual, it will depend on the BSP you are using but the section will be the same.

Also you could check this post from code aurora, busfreq-imx8mq.c

Hope this help you.

Regards,

Israel H.

[kinjalGediya]

Hello,
Thanks for your reply,

We tired to change ddr frequency using busfreq-imx8mq.c but we are unable to change ddr frequency.
Do you have any reference for chaining the ddr frequency using busfreq-imx8mq.c?

[nxf63675]

Did you also tried to do it bu follow the Linux manual? section 2.5.4 Dynamic Bus Frequency Link from the manual bellow:

https://www.nxp.com/docs/en/reference-manual/IMX_REFERENCE_MANUAL.pdf

Hope this help you,

Regards,

Israel H.

[kinjalGediya]

Hello nxf63675,

Thank you for reply,

1.

I have referred reference manual and make changes accordingly but ddr frequency doesn't changes. I have referred below patch for the make changes in the kernel.

2.

Also I have check below nxp community thread.

https://community.nxp.com/t5/i-MX-Processors/Change-LPDDR4-operating-frequency/m-p/862861

In above thread

dram_core_clk --- 000010a0 1 1 800000000 "dram_core_clk=800" means DRAM Clock=1600 (DDRC PHY PLL multiplies the input

we have checked on board its also showing: ----------------------------------------------------------------------------------

dram_pll1_ref_sel 1 1 0 25000000 0 0 50000

dram_pll_out 2 2 0 800000000 0 0 50000

dram_core_clk 1 1 0 800000000 0 0 50000

dram_alt 0 0 0 250000000 0 0 50000

dram_alt_root 0 0 0 62500000 0 0 50000

dram_apb 1 1 0 160000000 0 0 50000

------------------------------------------------------------------------------------

but when we probe DDR frequency in DSO, its showing pick at 800 MHz only.

[nxf63675]

Hi @kinjalGediya,

Can you please let us know how to reproduced the issue in an NXP. I.MX board.

Regards,

Israel H.