Quartus® II software version 10.1 will fail in the Fitter stage when you try to compile an ALTMEMPHY based DDR2 SDRAM High Performance Memory Controller generated by Quartus II 10.0 with following error:
Error: Source {Hierarchy_path}|{instance_name}_phy_alt_mem_phy_seq_wrapper:seq_wrapper|{instance_name}_phy_alt_mem_phy_seq:seq_inst|seq_mem_clk_disable drives port SRESET on atom
{Hierarchy_path}|{instance_name}_phy:{instance_name}_phy_inst|{instance_name}_phy_alt_mem_phy:{instance_name}_phy_alt_mem_phy_inst|{instance_name}_phy_alt_mem_phy_clk_reset:clk|DDR_CLK_OUT[0].mem_clk_ddio
There is no issue if you compile the IP in Quartus II software version 10.0.
To fix this issue, you need to regenerate DDR2 SDRAM High Performance Memory Controller in Quartus II software version 10.1.