quartus error

Note above code is a serilizer. You can do a desrializer on same basis.

I possibly got mixed up with serializer/deserilizer

important note:

Your desrialiser will not work since there is no indication of word beginning. You must send a signal from serialiser to indicate that, send it with the first bit. or use clk27 edge if properly aligned with data transition.

desrialiser

signal clk27_d : std_logic;
signal count : integer range 0 to 9;
 
process(reset,clk270)
begin
if reset = '1' then
   q <=  (others => '0');
   clk27_d <= '0';
   count <= 0;
elsif rising_edge(clk270) then
 
   clk27_d <= clk_27; -- for word boundary detection
 
   if clk27 = '1' and clk27_d = '0' then
      count <= 1;
   elsif count = 9 then
      count <= 0;
   else
      count <= count + 1;
   end if;
 
   q(count) <= data_in;
 
end if;
end process;