imx7s DDR frequency scaling

[tmeyer]

Hi

I have linux-fslc 4.1-1.0.x-imx running on my imx7 target. The busfreq driver is working as I can see the DDR freequency change between 24 and 533 MHz. However, the busfreq driver seems to be missing support for various other frequencies.

In the dts file changing  fsl,max_ddr_freq = <200000000> in "fsl,imx_busfreq", for example, hos no effect. I traced through the code and ended at  ddr3_freq_imx7d.S. This driver (unless I miss-read it) only handles 24, 100, & everything above 100 gets set to 533. I looked through th imx6 variant of this file and it seemed to have more support for the input clock frequency. 

Am I understanding this correctly? Is there a new version of this driver that supports other frequencies? Or do I change the  ddr3_freq_imx7d.S for my desired clock source and frequency?

Thanks in advance,

Tim

[igorpadykov]

Hi Tim

yes this is correct understanding, supported limited number of frequency

setpoints, please check description of bus frequency driver

in sect.24.1.2 Software Operation attached Linux Manual.

Best regards
igor
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