dump on mmcsd

Does mmcsd support kernel crash dumping?
>From my experience it does not.  Any attempt to dump to an SD card leads
to a hang with no diagnostic.  Maybe that depends on a controller?

>From reading the code, it seems that mmcsd_dump calls into the regular
write path and I could not find any special handling for the post-crash
environment (like polling instead of interrupts, etc).
Also, I see that mmc_da.c does not provide a dump method at the moment.

-- 
Andriy Gapon