We are using the ADV7842 as a front end digital video decoder. For determining the input HDMI resolution I have been reading the line width (hdmi registers 0x7 and 0x8) and field height (hdmi registers 0x9 and 0xA). However, for some resolutions the values are incorrect. Can anyone help explain why these registers are not giving the correct results?
Here are some resolutions I have tested and the values read from the line width and line height registers. Notice the line with and line height are correct for the SVGA and XGA resolutions but incorrect for the others.
Resolution line width, line height
800x600 60hz 800, 600
1024x768 60hz 1024, 768
1152,864 60hz 1280, 960
1280x768 60hz 1280, 960
1280x1024 60hz 1680, 1050