Raspberry PI sporadically fails to mount mmc card

[Bernd Walter]

On Wed, Aug 28, 2013 at 08:03:54AM +0200, Martin Laabs wrote:
> Hi,
> 
> Sporadically the raspberry pi fails to mount its root mmc card. After power
> off and power on again it works most of the time. However there seem to be
> also configurations that fail permanently. Unfortunately I have no image of
> a sd card that fails on every boot.

I see a similar very strange thing.

6 Raspi (256MB Eth Version) bought at the same time from same batch.
6 identic 8GB Transcent SD cards bought at the same time and likely
also same batch.

Used one card to copy crochet build image from r255729 source.
Booting fine, but identified as 1bit:
mmcsd0: 8GB <SDHC 00000 1.0 SN 16361806 MFG 06/2012 by 27 SM> at mmc0 25.0MHz/1bit/65535-block
On reboot it fails, but works on next boot without power down.

I'd tuned the installation and copy'ed the card to the 5 others.
None of the others were booting in the other raspi boards, but the
original card still worked in the original raspi.
All systems are running with power from same USB-hub.
Then I'd placed the working card in anther raspi and it failed as
well:
mmcsd0: 8GB <SDHC 00000 1.0 SN 16361806 MFG 06/2012 by 27 SM> at mmc0 50.0MHz/4bit/65535-block
mmcsd0: Error indicated: 1 Timeout
However it is probed with 4bit and higher bitrate.
This must be a very marginal problem when identic systems either
work or not.
Since the working condition is probed as 1 bit I wonder if there
is a generel 4 bit problem and addtional this single combo probes
wrong as 1 bit?

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.