SD card speed?

[Bernd Walter]

On Wed, Mar 21, 2007 at 06:14:24PM +0200, Krassimir Slavchev wrote:
> Hello,
> 
> I have made some test:
> 
> dd if=/dev/zero of=file.dat bs=1m count=10
> SD card on arm           - 10485760 bytes transferred in 41.431916 secs 
> (253084 bytes/sec)
> NFS mount from arm - 10485760 bytes transferred in 6.181458 secs 
> (1696325 bytes/sec)
> SD card on i386 PC    - 10485760 bytes transferred in 6.765610 secs 
> (1549862 bytes/sec)
> 
> The SD card is very slow on arm may be because it uses 1 bit bus.
> 
> Is there any problems with 4 bit bus support or my card is incorrectly 
> detected?

4-bit Support is not implemented yet.
I have a implementation and tried it once, but got data corruption
and hadn't retested, since this is not the main reason for low speed.
We don't do multiblock read/write so far, which is the main point.
Multiblock read is implemented, but deactivated, since it needs a
MCI workaround to be useable.
Multiblock write isn't implemented yet.
The whole story is on my TODO list, but my unfortunately ARM
development time is currently very limited because of other projects.

-- 
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