Update two points in the SPI interface documentation:
- Update description of the "chip stays selected after message ends"
mode. In some cases it's required for correctness; it isn't just a
performance tweak. (Yes: to use this mode on mult-device busses, another
programming interface will be needed. One draft has been circulated
already.)
- Clarify spi_setup(), highlighting that callers must ensure that no
requests are queued (can't change configuration except between I/Os), and
that the device must be deselected when this returns (which is a key part
of why it's called during device init).
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
f5a9c77df4