Detecting HDMI attach/detach with drm driver active?

[sgharms]

I'm trying to get hot resizing working. When I plug in HDMI monitor, extend the desktop; when I detach, collect all applications on my laptop. I thought that I could hook into devd(8)(), but I can't detect an event there (while I am doing just such a thing for USB attach/detach). I will note that I have the drm module for i915kms running. Is there a way to hook into that to detect an event that starts a reconfiguration?

I thought that xrandr(1)() might be the way, but right now, on my laptop on my couch it's showing:

$ xrandr|grep HDMI
HDMI-1 connected (normal left inverted right x axis y axis)


and I definitely do not have a cable long enough to run back to my desk to make that true!

 

[Phishfry]

Is there a way to hook into that to detect an event that starts a reconfiguration?

HDMI also contains I2C signalling for the HDMI handshake so maybe you could monitor i2c for chatter?

HDMI and I\$^2\$C

I was having a look at the HDMI pinout and I thought: why would they use I\$^2\$C for the display-host communication? My question here is about the design metrics that lead to this choice. HDMI is a

electronics.stackexchange.com

Difference between HDMI serial I2C and general I2C - Processors forum - Processors - TI E2E support forums

Other Parts Discussed in Thread: DM388 Hi , A very basic question. I am using DM388 processor in which I2C1 SDA SCL is muxed with HDMI SDA SCL. Is there any

e2e.ti.com

 

[Phishfry]

That don't look like it will work.

The DDC I2C channel is controlled by the HDMI core since it needs to handle HDCP transactions, hence is not directly accessible as an I2C channel.

 

[sgharms]

Thanks for the idea Phishfry.

 

[Phishfry]

The i2c-tools port has hooks into python. Even though encrypted just the presence of a signal exchange might be enough to give you a bone to pick on.