When there is no video stream on the link, or when there is no PCLK input from MAX96705, the PLL will not generate high frequence signal on the GMSL link, so there is no any data sent to MAX96706 via high frequence signal including IIC datas. So we can not read MAX96705 from host on MAX96706.
But MAX96706 can still write to MAX96705 because max96706 can send low frequency IIC signal. Use MAX06706 to set CLINK as 1 on MAX96705 will enable MAX96705's configure link. This can let MAX96705 send I2C data via low frequence IIC signal band.
In this way you can read MAX96705 from MAX96706 host side when there is no video stream on the link.