The vSync is off.
This is just a basic description of vSync:
Say your screen refreshes at 60Hz - vSync on will attempt to display 30fps to avoid tearing. 30 goes into 60 twice evenly... get it?
vSync off will display as many fps as possible. So rather than holding back and displaying 30fps it will allow 35fps. This will cause tearing because 35 does not go into 60 evenly.
So we have to enable vSync to avoid this..
Edit: The LG Optimus One kernel developer did it like this:
drivers/video/msm/mddi_hitachi_hvga.c pinfo->lcd.vsync_enable = TRUE; pinfo->lcd.hw_vsync_mode = TRUE;