現象
The Lid Switch BIOS option is newly added in BIOS 1.8.3 for Latitude 7390 2-in-1 and 1.7.4 for Latitude 5491 / 5591 / Precision 3530, and the default setting is set to disabled. When this BIOS version has been updated by the executable file you may notice the setting is enabled after applied the BIOS, and experience the system being unable to enter into sleep mode when the lid is closed regardless of the setting in the power management.
解決方法
As a workaround, please change the setting in the BIOS to load default and this will change to
disable.
A further BIOS update will be released to
Dell Drivers and Downloads soon to resolve this permanently and we recommend checking back for this new version.