Re: A20 emmc bad read/write

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, Jul 18, 2019 at 05:11:06PM +0200, Manuel Bouyer wrote:
> Hello
> is there anyone using an eMMC (not and sdcard) with an A20 board ?
> 
> I'm trying to use the on-board eMMC of a a20-olinuxino-lime2-emmc. The
> emmc is detected properly:
> [     2.173651] ld1 at sdmmc1: <0x15:0x0100:AGND3R:0x00:0x783ff444:0x000>
> [     2.173651] ld1: 14910 MB, 7573 cyl, 64 head, 63 sec, 512 bytes/sect x 30535680 sectors
> [     2.193661] ld1: 4-bit width, DDR52, 64 MB cache, 52.000 MHz
> 
> (the size matches the datasheet, and the CID looks OK).
> But when I try to use it the data are corrupted. More specifically,
> odd bytes are repeaed and even bytes are lost.
> For example if I write to the raw device 1234567890, I get back
> 1133557799:
> armv7# cat /tmp/f
> 1234567890
> armv7# dd if=/tmp/f of=/dev/rld1c conv=sync
> 0+1 records in
> 1+0 records out
> 512 bytes transferred in 0.002 secs (256000 bytes/sec)
> armv7# dd if=/dev/rld1c count=1|less
> 1+0 records in
> 1+0 records out
> 512 bytes transferred in 0.001 secs (512000 bytes/sec)
> 1133557799
> 
> (and 2 \n instead of one).
> 
> before I start looking closer, does it ring a bell to someone ?

Disabling SMC_CAPS_MMC_DDR52 makes it work properly. Of course with half the
speed. I could install NetBSD to the eMMC but I can't yet boot from it.

Linux doesn't seems to blacklist this controller, so I guess it should
be possible to have it working in DDR mode ...

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--