Dll-off mode for DDR3 on iMX7S

Technical Support
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1

Hello,

When going in to suspend to ram mode, does DDR3 being set to DLL-off mode to reduce frequency and current consumption?

Thanks,
Evgeny

2

Reading the suspend entry code, it does not seem to me that the SoC is explicitly set the MR1 register to set the DLL-off mode, see arch/arm/mach-imx/suspend-imx7.S.

There is some code for frequency scaling which seems to write the MR1 register, see arch/arm/mach-imx/ddr3_freq_imx7d.S.

Note we did not started to optimize memory suspend consumption since we still have rather high 3.3V power usage. We estimated RAM self-refresh usage to be around 14mW currently, the total memory consumption in suspend 62mW…

3

Is there another way (in the future) to reduce memory current consumption other than enabling DLL-off mode?

4

Not that we are aware of, no.