From: David Farrell <davidjf2001@ya...> - 2004-09-08 22:21:34
First, everyone who cares should read the license
for SD first. Basically it looks like you cannot
distribute any source code. If you distribute
binaries you need to be a member of sdcard.org
and you need a license for the product.
What I think is wrong with this. I downloaded a
Product Manual from SanDisk, a founding member of
sdcard.org which contains enough detail to get my
driver working. This manual was on an open web
server. There is no mention in this document
about license requirements, there is no
proprietary information notice. I think I am
safe! There are portions of the license that I
think imply that I can implement parts of the
spec without any license. I am not a lawyer and
I do not want to hire one. So what I think does
not matter, I have to play it safe.
The additional commands necessary to change a SD
card to a state which is compatible with MMC is a
trivial. Why did it not happen elsewhere? No-one
wants to be the test case I guess. In fact
Samsung, for their S3C2410 part had a SD/MMC
driver and changed the release to a MMC only
driver stating legal issues.
One last option I am considering is to run the
MMC form factor card in SPI mode. This is no big
penalty for the PXA255 since is has a SPI option
for the MMC controller. At first glance it
appears that no extra commands would be necessary
to run any card of this form factor.
This is a fair amount of work. U-boot is easy,
Linux is quite a bit more.