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AR# 53375

MIG 7 Series QDRII+ and RLDRAM II/3 - Timing paths from PHASER_IN to OSERDES are not analyzed due to missing clock definition

Description

Version Found: v1.7
Version Resolved and other Known Issues: See (Xilinx Answer 45195)

A number of timing paths within the MIG PHY are not being timed and will appear in the "unconstrained_endpoints" section of the report_timing_summary and check_timing reports:

RLDRAMII/3 example:

Checking 'no_clock'.
There are 18 register/latch pins with no clock driven by: u_mig_rldram/u_mig_7series_v1_7_rld_memc_ui_top_std/u_rld_phy_top/u_qdr_rld_mc_phy/qdr_rld_phy_4lanes_0.u_qdr_rld_phy_4lanes/qdr_rld_byte_lane_A.qdr_rld_byte_lane_A/PHASER_IN_inst.phaser_in/ICLK and possible clock pin by: rldiii_qk_n[3] rldiii_qk_p[3] 

There are 10 register/latch pins with no clock driven by: u_mig_rldram/u_mig_7series_v1_7_rld_memc_ui_top_std/u_rld_phy_top/u_qdr_rld_mc_phy/qdr_rld_phy_4lanes_0.u_qdr_rld_phy_4lanes/qdr_rld_byte_lane_A.qdr_rld_byte_lane_A/PHASER_IN_inst.phaser_in/ICLKDIV and possible clock pin by: rldiii_qk_n[3] rldiii_qk_p[3] 

There is 1 register/latch pin with no clock driven by: u_mig_rldram/u_mig_7series_v1_7_rld_memc_ui_top_std/u_rld_phy_top/u_qdr_rld_mc_phy/qdr_rld_phy_4lanes_0.u_qdr_rld_phy_4lanes/qdr_rld_byte_lane_A.qdr_rld_byte_lane_A/PHASER_IN_inst.phaser_in/PHASEREFCLK and possible clock pin by: rldiii_qk_n[3] rldiii_qk_p[3] 

...

There are 3 register/latch pins with constant_clock.

Checking 'unconstrained_endpoints'.

There are 264 pins that are not constrained for maximum delay.

There are 0 pins that are not constrained for maximum delay due to constant clock.

QDRII+ example:

Checking 'no_clock'.

There is 1 register/latch pin with no clock driven by: u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/incr_addr_reg_i_2/O and possible clock pin by: u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[0]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[10]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[11]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[12]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[13]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[14]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[1]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[2]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[3]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[4]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[5]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[6]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[7]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[8]/Q u_mig_qdr/u_mig_7series_v1_7_qdr_phy_top/u_qdr_phy_write_top/u_qdr_phy_write_init_sm/phy_init_cs_reg[9]/Q 

...

There are 3 register/latch pins with constant_clock.

Checking 'unconstrained_endpoints'.

There are 268 pins that are not constrained for maximum delay.

There are 0 pins that are not constrained for maximum delay due to constant clock.

Solution

These unconstrained_endpoints are a result of the Vivado timing tools not being able to propagate a clock to the ICLK/ICLKDIV output pins of the PHASER_IN.

Because these clocks are derived from the PHASERREFCLK, which is driven by CQ_P for QDRII+ designs and QK_P for RLDRAMII/3 designs, these clocks must be defined in the XDC constraint file. 

In order for the Vivado timing tools to properly analyze these paths, the following XDC constraint must be used:

QDRII+:

create_clock -period 2.500 -name phaserrefclk_phaser_in -waveform {0.000 1.2500} [get_ports {qdriip_cq_p[0]}]

create_clock -period 2.500 -name phaserrefclk_phaser_in -waveform {0.000 1.2500} [get_ports {qdriip_cq_p[1]}]

...

RLDRAMII/3:

create_clock -period 2.500 -name phaserrefclk_phaser_in -waveform {0.000 1.2500} [get_ports {qdriip_qk_p[0]}]

create_clock -period 2.500 -name phaserrefclk_phaser_in -waveform {0.000 1.2500} [get_ports {qdriip_qk_p[1]}]

...

Note: Adjust the period and hold time requirements accordingly to match your system.

Revision History
12/10/2012 - Initial release

AR# 53375
Date Created 12/07/2012
Last Updated 01/26/2015
Status Active
Type Known Issues
Devices
  • Kintex-7
  • Virtex-7
Tools
  • Vivado Design Suite
IP
  • MIG 7 Series