On Wed, Mar 19, 2014 at 11:43:55PM +0800, Axel Lin wrote:
> 2014-03-19 16:06 GMT+08:00 Geert Uytterhoeven <geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org>:

> > Just wondering: are there any SPI slave drivers that implement dummy cycles
> > this way?

> I think I found one such case:
> drivers/net/wireless/libertas/if_spi.c
> the dummy_trans has non-zero length, and both tx_buf and rx_buf are NULL.

> But that means it doesn't work with master drivers with this checking, e.g.
> all drivers using bitbang library has this checking.

I have to say that this seems rather abusive on the part of the driver,
it's going to cause implementation issues in the masters - I expect more
than just those that check aren't doing to do the right thing.