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Confused about DDR frequency in i.MX6 Solo

Question asked by Fernando Martinez on Aug 19, 2016
Latest reply on Aug 23, 2016 by Fernando Martinez

Hi all,

 

I've read several posts about DDR frequency, but there is one thing I don't understand. If I'm not wrong, the DDR clock is the clock named as MMDC_CH0_CLK_ROOT in the reference manual. The DDR clock frequency must be 400 MHz for the i.MX6 Solo processor. However, according to the reference manual, the default frequency for MMDC_CH0_CLK_ROOT is 528 MHz. I've used the DDR3 Script Aid to configure the DDR3 initialization, but I don't see at any time that CBCMR register is written for selecting PFD2 396 as clock source for MMDC_CH0_CLK_ROOT. So, I assume that if clock source is not changed, the DDR clock will be running at the default value (528 MHz), although the script is done for 400 MHz.

 

Also, I've been viewing other boards (e. g. Nitrogen6x) that have a DDR configuration file in u-boot done for i.MX6 Solo, and the change of clock source is never made. So, how is possible that DDR clock is running at 400 MHz?

 

Any clarification here, please? Thanks.

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