This property sets SAI sub-block as slave of another SAI sub-block.
Must contain the phandle and index of the sai sub-block providing
the synchronization.
+ - st,iec60958: support S/PDIF IEC6958 protocol for playback
+ IEC60958 protocol is not available for capture.
+ By default, custom protocol is assumed, meaning that protocol is
+ configured according to protocol defined in related DAI link node,
+ such as i2s, left justified, right justified, dsp and pdm protocols.
+ Note: ac97 protocol is not supported by SAI driver
The device node should contain one 'port' child node with one child 'endpoint'
node, according to the bindings defined in Documentation/devicetree/bindings/