552e450929
Now dw_spi core fully supports 3 transfer modes: pure polling, DMA and IRQ mode. IRQ mode will use the FIFO half empty as the IRQ trigger, so each interface driver need set the fifo_len, so that core driver can handle it properly Signed-off-by: Feng Tang <feng.tang@intel.com> Signed-off-by: Grant Likely <grant.likely@secretlab.ca>