Hi,

We make our final touch of A64-OLinuXino PCB and there we add option eMMC 
Flash to work on dual voltages 1.8V and 3.3V.
The eMMC is connected to AXP803 pin.34 GPIO1/LDO. The problem is that when 
A64 boots and AXP803 is not initialized it outputs default 0.8V then after 
initialization driver takes care to drive it  1.8V or 3.3V.
This makes impossible to boot from eMMC which is not good. We now think for 
solution which to drive eMMC at 3.3V initially when AXP803 output is below 
1.8V but this adds unnecessary hardware complexity.
For hardware point of view it will be much more simplier if dedigated A64 
GPIO is used and initially is pulled down and after AXP803 is initialized 
is pulled up.
How would you suggest us to implement it? Will this additional GPIO create 
troubles in eMMC driver philosophy?
For the SDMMC we are still hesitating what to do as we don't know if the 
card which will be inserted will support low voltage and higher speeds at 
all. Also eMMC Flash and SDMMC card should be driven by separate voltages, 
as they may work in any combinations.
This means we need another AXP803 LDO and another GPIO for the SDMMC card.

By the way the current eMMC from Micron we use has 11MB Write speed no 
matter what is the voltage and this is written in the datasheet, so maybe 
we should switch and add this dual voltage to the SD MMC where someone 
could use SD MMC card supporting higher clocks?

I would love to hear your opinion.

Tsvetan

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