J.D. Hodges

If you have a Dell Latitude running Windows 8.1 with an Unknown Device ACPI/SMO8810, this is the driver download link you need:

ST Microelectronics Free Fall Data Protection

This applies to all of these Dell laptops:
Latitude E5440 (Late 2013)
Latitude E7440 (Mid 2013)
Latitude E7240 (Mid 2013)
Latitude E5540 (Late 2013)
Latitude E7450 (Late 2014)
Latitude E5250/5250 (Late 2014)
Latitude E5550/5550 (Late 2014)
Latitude E5450/5450 (Late 2014)

And it is backwards compatible for the following OSes:

• MS Windows 7 32-bit
• MS Windows 7 64-bit
• MS Windows 8 32-bit
• MS Windows 8 64-bit
• MS Windows 8.1 32-bit
• MS Windows 8.1 64-bit (latest)

Screenshot of similar driver install:

Device manager showing the SMO8810 device after the correct driver has been installed