changing DRAM frequency on mainline kernel

[reverend_t]

Hi all

 

Given that the node that H3 consumption uses to change DRAM frequency no longer exists on H5 on the mainline kernel, how would one go about altering this?

[jernej]

1 hour ago, reverend_t said:

how would one go about altering this?

If you are ok with fixed lower frequency, you can rebuild U-Boot, or more specifically, SPL with wanted frequency and use that one instead.

[reverend_t]

Ah OK, so there are no userspace hooks for this? Would it involve editing the following file https://github.com/armbian/build/blob/master/patch/u-boot/u-boot-sunxi-dev/add-orangepi-zeroplus.patch for the OPi0+ and changing the DRAM lines:

 

 

@ -0,0 +1,22 @@

+CONFIG_ARM=y

+CONFIG_ARCH_SUNXI=y

+CONFIG_SYS_TEXT_BASE=0x4a000000

+CONFIG_SPL_SPI_FLASH_SUPPORT=y

+CONFIG_MACH_SUN50I_H5=y

+CONFIG_DRAM_CLK=624

+CONFIG_DRAM_ZQ=3881977

 

[jernej]

1 hour ago, reverend_t said:

Ah OK, so there are no userspace hooks for this?

No, unless you want to write a driver for completely undocumented controller with no or very little source code (reverse engineering ftw). It seems that something can be concluded from sunxi-dramfreq.c, which can be found in BSP kernel source, but AFAIK, no one works on that.

 

Yes, you have to change CONFIG_DRAM_CLK. But be very careful what you set here. Going up is completely discouraged.