How do I debug DisplayPort hotplug detection?
marius at gedmin.as
Tue Jan 14 04:16:03 PST 2014
I've got a Lenovo ThinkPad X220 with Intel graphics. When I plug in a
VGA cable, my desktop automatically notices it and reconfigures the
desktop. When I use a DisplayPort -> DVI cable, this doesn't happen and
I have to run xrandr by hand (with no arguments is fine, merely querying
RANDR makes the driver notice I plugged in the cable).
So far I filed an Ubuntu bug, tried to upgrade my BIOS (well, UEFI, I
suppose), tried the latest upstream kernel. No luck.
How can I debug this? Which component is supposed to detect these
events -- the kernel driver or the userspace bits in X.org? If it's the
kernel, what's the mechanism it uses to notify userspace about that
event? How does X notify clients about newly appearing monitors? What
command-line tools are there to watch for these events (not) showing up?
What's the appropriate upstream for this bug?
Well, there's a quantum computer that can factor 15, so those of you using
4-bit RSA should worry.
-- Bruce Schneier
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