2GB MMC/SD cards

Pierre Ossman
2006-05-29T14:00:34Z

Hi Russell!

Not sure when you'll be back from your trip, but I'll leave this hanging
in your inbox until then. :)

I've been getting several complaints about the issue with sector sizes
and large MMC/SD cards. I seem to recall we discussed this earlier, but
I cannot find those mail and I don't remember our conclusions.

I do, however, have the following in both the SD and MMC card specs I
have (both sandisk though):

WRITE_BL_PARTIAL — defines whether partial block sizes can be used
in block write commands.

Table 3-25
WRITE_BL_PARTIAL Definition
0 Only the WRITE_BL_LEN block size, and its partial
derivatives in
resolution of units of 512 blocks, can be used for
block oriented data
write.
1 Smaller blocks can be used as well. The minimum
block size is one
byte.

So perhaps we should remove all the funky logic that's in mmc_block.c
right now and just always select a block size of 512 bytes? People have
been reporting that their Palms, cameras and USB readers will not accept
anything else.

Rgds
Pierre