After a bunch of digging around trying to find out how to get my internal SD card reader working in Ubuntu 10.10 I have found this solution:
Looking at dmesg, the error I was getting was this:
mmc0: ADMA error mmc0: error -5 whilst initialising SD card
I found the solution here:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/660088
cd /etc/modprobe.d sudo vim sdcardread.conf
[ctrl]+[i] to put vim into insert mode
Now you need to paste this line into the file and save:
options sdhci debug_quirks=0x40
then hit [esc] to exit insert mode, then type
:wq
to save the file and quit.
now you need to run these commands
sudo rmmod sdhci_pci sudo rmmod sdhci sudo modprobe sdhci sudo modprobe sdhci_pci
Then if you re insert your SD card and view dmesg, you should no longer see the error message
dmesg
This worked great for me on a Dell 6410 64-bit running Ubuntu 10.04.
Remember to put a at the end of the line in the file sdcardread.conf. I missed it the first time and it failed.