The sna acceleration is default option and I want to go back to uxa because sna doesn't work after suspending on my laptop.
And it doesn't work just adding /etc/X11/xorg.conf.d/20-intel.conf which contains 
"Section "Device"
   Identifier  "Intel Graphics"
   Driver      "intel"
   Option      "AccelMethod"  "uxa"
EndSection"
to make the switch.
After input: cat /var/log/Xorg.0.log | grep -ie uxa -ie sna in terminal. The output is:
[     4.142] (II) intel(0): SNA compiled: xserver-xorg-video-intel 2:2.99.910-0ubuntu1.6 (Timo Aaltonen <tjaalton@debian.org>)
[     4.144] (II) intel(0): SNA initialized with Broadwell backend
And it seems that the UXA is not compiled or installed at the beginning.
Is there a way to switch to UXA under this situation?
 
     
    