[Intel-gfx] TV detect

[Peter Clifton]

Does anyone know what the expected (s-video output) electrical waveforms
for a "correct" load-detect look like (with / without output connected).
I can probably hook up a scope in the lab to verify whether they are
getting out of the chip OK.

Do the DAC outputs sit at 0.7V DC? What are the timing requirements for
the sensing?


I see a few possibilities for the miss-detection..

1. Not waiting long enough for the load detect pipe's PLLs to come up
before trying to use it to detect the TV-connection.

2. Not waiting long enough for the DACs to switch on / stabilise ->
under voltage level when we detect -> misdetect.

3. Laptop specific hardware issues (presenting some phantom load or
"noise" which is near the detection borderline)

4. Correct detection depends on a more comprehensive register set-up, or
other bits of state within the TV-out circuitry. I guess the hardware
guys would know more about how the load detection works inside the chip,
hence what prerequisites there are.

(Although, as far as I can see / infer, there is a full mode-set to NTSC
480i before detection commences).

5. Evil penguins flipping bits inside the chip.