Hi ChenYu,
I am sorry.
We just run DDR8 40MHz on A31/A31s with MMC3.
If you run it with MMC2, it not support DDR8 function.
You should switch pinmux to MMC3.
If you want to try DDR 50, you can improve IO voltage to 3v.
And, you should set mod clock(in ccmu) and card clock(in mmc controller) in
following different scenarios:
a. 8 bit width:
source clock must be double card clock, it mean CCLK_DIV is 2.
(Card Clock) = (MMC Module Clock) / 2
b. 4 bit width:
Card Clock = MMC Module Clock
Best regards
Sugar
On Thursday, December 10, 2015 at 3:17:44 PM UTC+8, Chen-Yu Tsai wrote:
>
> Hi,
>
> I am working on DDR support for the MMC controllers.
> Unfortunately none of my boards support signal voltage switching to 1.8V,
> (and I suspect no boards do), so I cannot try out UHS-1 modes.
>
> I have 4 boards that have eMMC chips connected to MMC2.
> These are the A80 Optimus, Cubieboard4, Sinlinx SinA33, and SinA31s.
> eMMC DDR 52 is working on all but the SinA31s. The delay values
> from Allwinner kernel sources do not work.
>
> Can Allwinner provide the delay values for A31/A31s MMC2 DDR50?
>
> Ongoing work can be found here:
>
> https://github.com/wens/linux/commits/sun9i-wip
>
> If anyone knows of any boards that support SD card voltage switching,
> please let me know.
>
> Regards
> ChenYu
>
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