Hello,
PLM_CTRL register has three kind of override fields.
What is the difference between VALID_OVERRIDE, HSYNC_OVERRIDE and VSYNC_OVERRIDE settings?
From IMX8DXAEC.pdf (Rev.0):

Copy from linux/drivers/media/platform/imx8/mxc-mipi-csi2.c

Best Regards,
Kazuma Sasaki.