Comment 9 for bug 1861521

I enabled the KMS debug messages in the drm module:

$ cat /etc/modprobe.d/drm-debug.conf
options drm debug=0x04
$ sudo update-initramfs -u -k $(uname -r) && sudo reboot
...

Unfortunately, it doesn't look like my device_id is set after the drm_dp_read_desc() in drm_dp_read_desc:

$ dmesg | grep -i OUI
[ 1.378026] [drm:drm_dp_read_desc [drm_kms_helper]] DP sink: OUI 38-ec-11 dev-ID HW-rev 0.0 SW-rev 0.0 quirks 0x0000

Hopefully the device_id is set for the Dell platform in bug #1856134 so that commit 3269788061d2 ("USUNTU: SAUCE: drm/i915: Force DPCD backlight mode on Dell Precision 4K sku") can be more specific to that device.