On Fri, Dec 11, 2015 at 10:41 AM, Sugar Wu <
shuge...@gmail.com> wrote:
> 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.
Interesting. Is this a hardware difference between MMC2 and MMC3?
Or is it just signal routing problems?
Anyway I got DDR8 working on my A31s. Thanks!
> 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
Yes. I noticed this from the SDK. With this already 8 bit works on A33 / A80.
I also noticed A33's "new timing mode", but I can make DDR work without it,
using old timing mode.
Regards
ChenYu
>
> 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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