Comment 41 for bug 1714178

my patch is not acceptable,
Refer to the last comment from Ville Syrjälä
 "
 Even if this would be correct (which it's not for most platforms at
 least, not quite sure about the very latest hardware), anyone doing
 this should at least do a cursory check of the relevant math in the
 driver to make seure we don't end up with integer overflows.
 "

This change is for https://bugs.freedesktop.org/show_bug.cgi?id=102508 , and the hardware configuration is

* 00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:591d] (rev 04)
* Dell Thunderbolt BME dock : http://www.dell.com/support/article/us/en/04/sln301105/dell-thunderbolt-dock--tb16--information-and-specifications?lang=en
* internal native monitor is 4K, another 2 4K monitors are plugged behind BME dock

This patch could let this setting work, but looks it not the correct way.
Not see the the relevant math in original code of commit b321803dfb and ac484963f9 .
Does someone know how the original value 8192 be calculated out?
So that the way might could be followed for this new change.