I'm setting up the 7842 in Component YPbPr mode, and monitoring the CP lock, CP unlock and STDI valid interrupts to detect changes in the input format. When I receive these interrupts, I check the STDI Valid status bit, and then read the Component HFreq and Total height registers to determine the new input format. If this is a format valid for our device, I update the settings for VID_STD and output frequency to have the 7842 output this new format. If the format is not valid for our device, I make no changes, allowing the 7842 to free run and generate a default solid colour.
If I update the VID_STD settings and output frequency to output the newly detected format, I then continue to receive interrupts as expected. However, when I leave these settings at their previous values to enable the 7842 to free run and generate a default solid colour, I no longer receive interrupts when the input format changes again. If I poll the STDI Valid, Component HFreq and Total Height registers, then I do see changes as expected.
How can I continue to receive these interrupts when the part is free running? I'm trying to avoid polling if I can avoid it.