Linux/DS90UB964-Q1: I can't read registers for 913/ov10640.

Part Number:DS90UB964-Q1

Tool/software: Linux

hi ti

 4*ov10640->4*du90ub913->ds90ub964->ov490

After setting, I can use ov490 to read and write 913 and ov10640 registers through 964, but at present I can only read 913 and ov10640 registers of port 0 and 1, and the values of registers read from ports 2 and 3 are all 0xff.

I select the port by setting the value of register 0x4c of 964.

port 0    write964(0x4c,0x01)

port1    write964(0x4c,0x12)

port 2    write964(0x4c,0x24)

port 3    write964(0x4c,0x38)

Reg[0x00]->data[ff] 

The data read is shown above.

I want to know why I can read the data of ports 0 and 1, but can't read the data of ports 2 and 3??

thanks.