How to adapt HiDPI screen with lightdm-deepin-greeter?

[amit-gshe]

The font in login screen is small and I tried adding a file: /etc/lightdm/deepin/hidpi.conf:

$ cat /etc/lightdm/deepin/hidpi.conf 
[greeter]
xft-dpi=260
enable-hidpi=auto

But it seems not work this way.