The TW9910 PDN gpio (power down) is listed as active high in the chip
manual. It turns out it is actually active low as when set to physical
level 0 it actually turns the video decoder power off.
Without this patch applied:
tw9910 0-0045: Product ID error 1f:2
With this patch applied:
tw9910 0-0045: tw9910 Product ID b:0