As per this thread, when we see an input to the 7842 that we don't support, I am trying to allow the part to free run at the currently set VID_STD, to continue to generate a default blue screen at a supported output resolution.
If I set the part up to generate a 1080i50 output with an appropriate 1080i50 input connected (VID_STD set to 0x14) then I get a valid output. If I then switch to 1080p50 input and make no changes to the VID_STD register, I would expect to see a blue screen output at 1080i50. However, the TV connected to my eval board now reports 'Unsupported format' (it should still be displaying at 1080i50, and I've proved that it can accept this format). I tried forcing the part into free run mode (setting bit 0 of register 0xbf in the CP map) and I see the same behaviour.
The CP_STATUS register does indicate that the part is free running. However, the value of 0x99 is slightly confusing, as this suggests that it is seeing macrovision pseudo sync pulses. Could this be the cause of the issue?
If I *do* update the VID_STD to be 1080p (0x1e) then I get a 1080p50 output on the display (although there is some interference on the image).
Can you tell me how I can get this working?