For Arria10* it solves the not-working I2C issue: bidirectional pin

drive out '1' instead of 'Z'. It also removes the Warning (12620): Input port OE of I/O output buffer is not connected, but the atom is driving a bi-direct...

libraries/io/i2c/src/vhdl/i2c_smbus.vhd

@@ -137,6 +137,13 @@ ARCHITECTURE rtl OF i2c_smbus IS
   SIGNAL timeout       : STD_LOGIC;
   SIGNAL nxt_timeout   : STD_LOGIC;
 
+  -- Attributes for Quartus. Fixes the issues:
+  -- - For Arria10* it solves the I2C issue: bidirectional pin drive out '1' instead of 'Z'
+  -- - Removes the Warning (12620): Input port OE of I/O output buffer is not connected, but the atom is driving a bi-direct...
+  attribute keep: boolean;
+  attribute keep of scl_o: signal is true;
+  attribute keep of sda_o: signal is true;
+
 BEGIN
 
   -- CONSTANT Signals dependent on GENERIC Signal gs_sim