[Libdlo] GDM black screen / user and count meaning

[Alexander Todorov]

Some more thoughts on my side, not sure if helpful:

The dlfb_ops_blank() function always calls dlfb_enable_hvsync(bufptr, false)
if blank_mode != FB_BLANK_UNBLANK

The dlfb_enable_hvsync() function looks like:

/*
  * On/Off for driving the DisplayLink framebuffer to the display
  *  0x00 H and V sync on
  *  0x01 H and V sync off (screen blank but powered)
  *  0x07 DPMS powerdown (requires modeset to come back)
  */
static char *dlfb_enable_hvsync(char *buf, bool enable)
{
         if (enable)
                 return dlfb_set_register(buf, 0x1F, 0x00);
         else
                 return dlfb_set_register(buf, 0x1F, 0x07);
}


This function doesn't process the 0x01 value which is described in the comment.

Further more in fb.h there are comments (around FB_BLANK_* definition) pointing 
out that hsync and vsync can be on/off in various combinations. Why doesn't 
dlfb_enable_hvsync() account for those as well?


Regards,
Alexander.