My RCW configures two SerDes lanes as XFI. I would like to reconfigure these lanes as SGMII or 1000Base-X. Is it possible to do this via reconfiguration of the SerDes control registers?
All supported SerDes configurations are shown in the T2080RM, Table 19-1. SerDes Lanes Assignments and Multiplexing.
Other configurations are not supported.
Section 19.6 of the RM, particularly Section19.6.4, indicate that the SerDes can be reconfigured after POR RCW configuration by writing to the appropriate SerDes registers (assuming the necessary RefClk and PLL frequencies are available). I am misinterpreting this section?
Which SerDes protocol pair is in question?
For example, table 19-1 has no SRDS1: A/SG9 - B/SG10 - C/XFI1 - D/XFI2 (I don't care about E,F,G,H). Going through the SerDes register settings, this looks like it could be configured as long as I use PLL1 for lanes 0/1 and PLL2 for lanes 2/3. (I know there is a XFI/XFI/SG/SG configuration in the table, but I am trying to support my current board connections.)
> SRDS1: A/SG9 - B/SG10 - C/XFI1 - D/XFI2
This configuration is not possible because XFI lanes always use PLL1 and lanes A & B also always use PLL1.
Looking at the descriptions for the Serdes General Control Register 0 SerDesx_LNnGCR0, I see that lanes A & B must use PLL1, but that I can also set lanes C - H to use PLL2. I can't find any SerDes register description that requires XFI to use PLL1 (other than the RCW table). Is this limitation documented somewhere? I may be missing it. Thanks.
Response from the Applications Team:
"We don't have this option in RM and they cannot use this combination. We only support the options published in RM."
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