Caliptra JTAG TdoEn missing output

[nstewart-amd]

“IEEE1149.1 standard says in chapter 4.5.1 “The TDO driver shall be set to its inactive drive state except when the scanning of data is in progress”. So TdoEn is needed to implement this requirement, detailed in Table 6.2.”

Caliptra RTL currently does not expose TdoEn as a top-level port.
However, TdoEn appears to be implemented in the VEER TAP controller.

File: riscv_core/veer_el2/rtl/dmi/rvjtag_tap.v
assign tdoEnable = shift_dr | shift_ir;

However, this output is left dangling at the VEER wrapper and not pulled to the top of Caliptra.

File: riscv_core/veer_el2/rtl/el2_veer_wrapper.sv
.tdoEnable (),

[nstewart-amd]

Also here: chipsalliance/Cores-VeeR-EL2#159

[steven-bellock]

Somewhat related issue : #365 (just get rid of the VeeR TAP controller since SoCs have their own). In particular VeeR (and Caliptra) assume that the TAP signals go directly to the chip's pins/pads.

[Nitsirks]

I've submitted a PR to fix this issue

#423