Hello liuhui,
settle-cnt sets the Ths-settle parameter as per MIPI D-PHY spec (the time that the receiver waits after LP-00 state and before it starts looking for the Leader-Sequence).
settle-cnt is calculated by the formula:
settle-cnt = Ths-settle [ns] / csiphy0_timer_clk [GHz]
The csiphy0_timer_clk is set to 200MHz (0.2GHz).
Ths-settle you have to determine based on your sensor settings.
Then calculate the settle-cnt.
u8 vc = 0; - this is the Virtual Channel Identifier as per MIPI CSI-2 spec that the sensor uses for the frame data. Usually sensors use virtual channel 0 by default and/or the sensor can be configured which virtual channel to use. Set this value the same as the virtual channel which your sensor uses.