P2040/P2041 PCIe Specific FAQs

Document created by Omar Cruz Lopez Employee on Aug 6, 2012Last modified by Omar Cruz Lopez Employee on Aug 6, 2012
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If I select a SerDes Mux config using a PCIe controller on 2 lanes, is it possible to use just one lane, although it is configured to two lanes PCIe? Do you have any advice for such configuration?

A13. Yes, it is possible to use just one lane while selecting SerDes Mux config using a PCIe controller. From the P2040 SERDES options ECI will be setting PCIe2 to use lanes E & F. If you have them pinned out to x2 connector then it will automatically train down to x1 if a x1 device is inserted. If you don't want to use lane F then power lane F down during reset and set SRDSPCCR0[PEX2_CFG] to x1.


What is the function of TRSTDIR bit found in Table 3-26/B1GCRA1–B1GCRJ1 Field Descriptions B1GCRA1 [TRSTDIR] in P2041 RM?

It controls Lynx Tx lane reset function for multi-lane protocols. For multi-lane protocols where the lanes are from left to right (PEX, XAUI), it should be set to 1 while for protocols where the lanes are from right to left (SRIO, Aurora), it should be set to 0. For single-lane protocols (SGMII, SATA) it doesn’t matter. It is paired with BnGCRm0[1STLANE], which determines the master source clock lane for a multi-lane protocol (must always be =1 for nominal lane 0 for the protocol, e.g. lane A for PEX on lanes A-D, and =0 for all other lanes).


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