2 FOM2

The Figure of Merit (FOM2) computation is a computed score used to grade the PCIe SerDes eye quality in terms of Bit Error Rate (BER). Scoring determines a pass, marginal, or fail in terms of probabilistic BER. The FOM2 is correlated to the Rx Jitter Tolerance (JTOL) over all PVT data.

Table 2-1. Pass/Fail Criteria for FOM2 Scores
Parameter	Description
FOM <= 85	High possibility of bit errors
85 < FOM < 110	Low possibility of bit errors
FOM >= 110	No bit errors

The FOM2 operates when there is a change in the PCIe link state. The FOM for each lane is constructed based on two register reads as follows:

The FOM2 = 3*FOM_AFE_EYEH + MM_FOM

Where:

FOM_AFE_EYEH: is read from register DIG_RX_CTL_RX_ADAPT_MM_FOM.RX_ADAPT_MM_FOM

MM_FOM: is read from register DIG_RX_CTL_FOM_CTL.FOM_AFE_EYEH