Changes between Version 8 and Version 9 of newport/PCIe


Ignore:
Timestamp:
04/12/2019 11:47:33 PM (6 years ago)
Author:
Tim Harvey
Comment:

updated notes about PCIe gen2/3

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  • newport/PCIe

    v8 v9  
    3535[=#throughput]
    3636== PCIe Throughput ==
    37 The CN80XX/CN81XX PCIe host supports up to PCI Gen3 (8.0GT/sec or 6.4Gbps) however this requires a higher co-processor (SCLK) speed (550MHz) than is configured by default (350MHz) on standard Newport boards. This is a resistor loading option thus can't be changed by software. The decision to default to 350MHz supporting Gen2 (5.0GT/sec or 4Gbps) was made because it saves approximately 500mW of power consumption and the lack of Gen3 miniPCIe card availability.
     37The CN80XX/CN81XX PCIe host supports up to PCI Gen3 (8.0GT/sec or 6.4Gbps) however this requires a higher co-processor (SCLK) speed (550MHz) than is configured by default (350MHz) on some standard Newport boards. This is a resistor loading option thus can't be changed by software. The decision to default to 350MHz supporting Gen2 (5.0GT/sec or 4Gbps) was made because it saves approximately 500mW of power consumption and the lack of Gen3 miniPCIe card availability.
    3838
    3939By default Newport boards support PCI Gen2 (5.0GHz/sec or 4Gbps) which is backwards compatible with PCI Gen1 (2.5GT/sec or 2Gbps).
    … …  
    4141If you are interested in utilizing PCIe cards up to Gen3 performance (8.0GGT/sec or 6.4Gbps) please contact sales@gateworks.com. A resistor modification is required on the board to do move SCLK from 350MHz to 550Mhz.
    4242
    43 Note that the GW640x boards have a coprocessor clock running at 550MHz but still configure PCIe for Gen2 rates. Therefore on a GW640x you can modify the QLM-FREQ.N0.QLM* proprety in BDK device-tree file bdk/boards/gw6404.dtsi to specify 8000 MHz for Gen3.
     43Note that the GW640x boards have a coprocessor clock running at 550MHz required for the QSGMII phy and as such the GW640x will configure the PCIe host controllers for 8.0GT/sec for Gen3 rates.
    4444
    4545The bus speed represents a theoretical maximum throughput and does not account for host processing speed or bus contention from multiple masters.