On Wed, Mar 19, 2014 at 09:06:31AM +0100, Geert Uytterhoeven wrote:
> On Wed, Mar 19, 2014 at 4:53 AM, Axel Lin <axel.lin-8E1dMatC8ynQT0dZR+AlfA@public.gmane.org> wrote:

> > Reject transfer if both tx_buf and rx_buf are NULL for non-zero length transfer.
> > Add the checking in spi core so we can remove the same checking in various
> > drivers.

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

The ChromeOS EC apparently does this.