I always thought the support for multiple logical SCSI units in the USB
mass storage class was a dead feature. Turns out that it's actually used
by SD card readers that provide multiple slots (e.g. one regular sized
and one micro-SD). Implementing perfect support for that would require a
major redesign of the whole MSC stack, since the one device -> one disk
assumption is deeply embedded in our data structures.
Instead, this patch implements a poor man's LUN support that will just
cycle through all available LUNs (in multiple calls to usb_msc_poll())
until it finds a connected device. This should be reasonable enough to
allow these card readers to be usable while only requiring superficial
changes.
Also removes the unused 'protocol' attribute of usb_msc_inst_t.
BRANCH=rambi?,nyan
BUG=chrome-os-partner:28437
TEST=Alternatively plug an SD or micro-SD card (or both) into my card
reader, confirm that one of them is correctly detected at all times.
Change-Id: I3df4ca88afe2dcf7928b823aa2a73c2b0f599cf2
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/198101
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
960534a20e