URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [orpsocv2/] [boards/] [xilinx/] [atlys/] [rtl/] [verilog/] [xilinx_ddr2/] [xilinx_ddr2_if.v] - Rev 677

Rev	Log message	Author	Age	Path
677	atlys: add 2-clock synchronizer chain for ddr2_calib_done The signal ddr2_calib_done signal comes from the ddr2 clock domain, while wb_req is treating it as if it came from wb_clk domain. As a result the timing analysis tool assumed a worst case scenario of 5ns between the two domains and the results were miserable. While we can argue that this is a multi-cycle path, the fact is that ddr2_calib_done feeds into multiple logic sinks and can potentially cause meta-stability issue in the design. The solution is to add a 2-clock meta-stability filter to address both the timing problems and the meta-stability concern. Signed-off-by: Jason Zheng <jxzheng@gmail.com> Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> Acked-by: Olof Kindgren <olof.kindgren@orsoc.se>	stekern	4670d 09h	/openrisc/trunk/orpsocv2/boards/xilinx/atlys/rtl/verilog/xilinx_ddr2/xilinx_ddr2_if.v
627	orpsoc: add Digilent Atlys spartan6 board rtl Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>	stekern	4851d 22h	/openrisc/trunk/orpsocv2/boards/xilinx/atlys/rtl/verilog/xilinx_ddr2/xilinx_ddr2_if.v