[MS2130] Hot Plug Detect

[bartsch]

Hi, not an issue, but a detail others might be interested in and this repository seems to be a good place for sharing.

I have found that one is able to change the hot plug detection pin state with register 0xf015 by setting/clearing bit 3.

Pseudocode for clarification:

HDMI_HPD_REG = 0xf015
HDMI_HPD_MASK = (1 << 3)

value = read(HDMI_HPD_REG)

# disconnect (set bit 3)
write(HDMI_HPD_REG, value | HDMI_HPD_MASK)

# connect (clear bit 3)
write(HDMI_HPD_REG, value & ~HDMI_HPD_MASK)

The fun part comes, when you exchange the EDID inbetween the disconnect and connect. The EDID can be changed on the fly as demonstrated here: steve-m/hsdaoh

Be aware that one shouldn't poke registers while the HDMI source establishes a new signal (reading EDID etc). This breaks EDID transmission once in a while and/or leads to flaky resolution states.

Cheers,
Daniel

[amalinowski75]

Thank you @bartsch! That helped me a lot. Thanks to that I can make the video source reread EDID after I upload a custom one to MS2131.