[Intel-gfx] TV detect
pcjc2 at cam.ac.uk
Mon Jan 4 18:17:34 PST 2010
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
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.
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