I am quite used to install operating system updates on deb and rpm based Linux distros. This is usually a simple update && upgrade. But firmware updates on Linux is a pain in the ass, until now I discovered recently on my new laptop. Thanks to "Linux Vendor Firmware Service" aka LVFS. Check out the steps below how to proceed on the CLI. The next time I will try the GUI version to apply firmware updates, because the GNOME or Ubuntu software app is also capable of interacting with LVFS.

Refresh fireware soucres:

djvl@antares ~> sudo fwupdmgr refresh
Fetching metadata https://cdn.fwupd.org/downloads/firmware.xml.gz
Downloading…             [***************************************]
Fetching signature https://cdn.fwupd.org/downloads/firmware.xml.gz.asc

djvl@antares ~>

Check if there are updates and what it is about:

djvl@antares ~> sudo fwupdmgr get-updates
XPS 13 7390 System Firmware has firmware updates:
GUID:                    cbe49cca-492b-93e8-b0f4-f693501f271b
ID:                      com.dell.ueficbe49cca.firmware
Update Version:          0.1.2.0
Update Name:             XPS 13 7390 System Update
Update Summary:          Firmware for the Dell XPS 13 7390
Update Remote ID:        lvfs
Update Checksum:         SHA1(d5bc6341420db669e19955b38a2083ed7121b184)
Update Location:         https://fwupd.org/downloads/945e4e936f974e958ac0bc9c7129707e76cc5660-XPS_13_7390_1.2.0.cab
Update Description:      This stable release fixes the following issues:
                         
                          • Fixed the issue where the keyboard and touchpad does not work when connecting an external monitor.
                          • Fixed the issue where the touchpad lags when the system goes to idle mode from modern-standby mode.
                          • Fixed the issue where the touchpad stops responding once the lid is closed.
                          • Fixed the issue where the system displays a warning message when resumed from hibernation or is turned off.
                          • Fixed the issue where the system displays diagnostics indicators during BIOS recovery.
                          • Fixed the issue where the system displays a black screen when it is put to sleep/shutdown/restart mode.
                          • Fixed the issue where the system stops responding and displays a black screen when lid is closed during POST.
                         
djvl@antares ~>

I really like the fix which says: "Fixed the issue where the touchpad stops responding once the lid is closed." Is it me not getting this?

Apply the update:

djvl@antares ~> sudo fwupdmgr update
Downloading 0.1.2.0 for XPS 13 7390 System Firmware...
Fetching firmware https://fwupd.org/downloads/945e4e936f974e958ac0bc9c7129707e76cc5660-XPS_13_7390_1.2.0.cab
Downloading…             [***************************************]
Decompressing…           [***************************************]
Authenticating…          [***************************************]
Updating XPS 13 7390 System Firmware…                            ]
Scheduling…              [***************************************]

An update requires a reboot to complete. Restart now? [Y|n]:
djvl@antares ~>

Reboot en cross fingers :)

It worked flawless, but took quite some time..