gma skl: Disable DDI clocks on reset path

After reset DPLL_CTRL2 is initialized to 0. Which means some clock
disable bits are not set and might cause some hassle later. Set them
and close the related TODO.

Change-Id: I1a470dff55e317e8119906b3e397f6f2314abcbd
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/20648
Tested-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
diff --git a/common/haswell_shared/hw-gfx-gma-connectors-ddi.adb b/common/haswell_shared/hw-gfx-gma-connectors-ddi.adb
index 0fc4ad9..fa62a98 100644
--- a/common/haswell_shared/hw-gfx-gma-connectors-ddi.adb
+++ b/common/haswell_shared/hw-gfx-gma-connectors-ddi.adb
@@ -747,4 +747,18 @@
       end if;
    end Off;
 
+   ----------------------------------------------------------------------------
+
+   procedure Post_Reset_Off
+   is
+      Clocks_Off : Word32 := 0;
+   begin
+      if not Config.Has_Per_DDI_Clock_Sel and not Config.Has_DDI_PHYs then
+         for Port in Digital_Port loop
+            Clocks_Off := Clocks_Off or DPLL_CTRL2_DDIx_CLOCK_OFF (Port);
+         end loop;
+         Registers.Set_Mask (Registers.DPLL_CTRL2, Clocks_Off);
+      end if;
+   end Post_Reset_Off;
+
 end HW.GFX.GMA.Connectors.DDI;