We are using the TUSB7320 in an embedded board application (not a PCIe adapter card), and cannot enumerate the device over PCIe.
Power-up sequence looks correct, with GRST# deasserted about 3 msec after both supplies are stable. PERST# is deasserted about 200msec after deassertion of GRST# and presence of ref_clk. Recommended 48MHz crystal topology is being used.
1. Can ref_clk be present before GRST# is deasserted? (Not clear from Figure 3-1 in datasheet.)
Being an embedded application, neither WAKE# nor CLKREQ# support is required. Both pins are unconnected in the design.
2. Is this an issue given the erratum regarding oscillation of the ESD structure? Could this affect our ability to enumerate the part over PCIe?
Both 3.3V (i/o) and 1.1V (core) supplies are derived from low-noise switching supplies (TPS54626PWP & TPS54320RHL). An LC similar to that of the Demo EVM (SLLU146C) is used on the analog supply. Proper decoupling and bulk capacitor recommendations have been followed throughout).
3. Could any supply noise affect our ability to enumerate over PCIe?
