Compute Module • Re: CM4S -- Sometimes card0-HDMI-A-1, sometimes card1-HDMI-A-1

I would like to poll `/sys/class/drm/cardx-HDMI-A-1/dpms` to know whether or not the turn off the display's backlight. If you wish to read the thread at viewtopic.php?p=2182080, you'll see that it's not currently possible for me to use the ordinary backlight driver for that.

@PhilE suggested at viewtopic.php?p=2123544#p2123544, that one could query the `/sys/class/drm/` to sync DPMS and the backlight, and given the troubles I've had using the ordinary backlight driver, querying `/sys/class/drm/cardx-HDMI-A-1/dpms` seems like the simplest, and even the most reliable, way to get that to work.

I also need to support several models with differing hardware, so querying `/sys/class/drm/cardx-HDMI-A-1/edid` is a convenient way to determine which model the software is running on, as we are encoding that information in our EDIDs.

Statistics: Posted by JinShil — Tue Feb 13, 2024 4:07 am

---