Detect HDMI Hot plug at user space

Autonomous Machines Jetson & Embedded Systems Jetson Xavier NX
1

HI, All

we have a question about HDMI Hotplug at Jeston NX

we want to provide user-space application a mechanism /event to know HDMI cable is plug or unplugged,
but we don’t konw how to implement at the driver level as well as user-space framework,
any code can we refer at Linux?

 Thanks for advance

BRs
Stephen

3

Moving into Jetson Xavier NX forum for resolution. Thanks

4

Hi,

You could use the udev event to know what might be a hotplug event. Since hotplug will change the status of external-connection:disp-state, you can use it to tell.
If NAME of the extcon event matches to “external-connection:disp-state” consider it as HOTPLUG event.

5

thanks, could you name the driver who implemented this hotplug and change the status of external-connection:disp-state? our case is a little bit different with HDMI output which Jeston is HDMI source, our case is we have an HDMI to MIPI bridge chip on our carrier board, HDMI into jeton NX , so from Jeston side it is HDMI in , HDMI bridge chip is sink. This bridge chip provides HPD detection functionality, it notifies us by GPIO interrupt, we now only have a V4L driver to receive MIPI video from a bridge, but we need implement it at driver HPD first. right?

6

Please check our kernel source with path kernel/nvidia/drivers/video/tegra/dc. All the display kernel driver is in this location.