#51 JTAG operations hang with libftdi

[Arnim Läuger]

Initial JTAG operations hang after init when using the ft2232 cable with ftdi-mpsse.
Different systems exhibit different behavior:

System A
No hangs with r1106, but begins to hang when ftdi_set_latency_timer() in ftdi_mpsse_open() is increased from 16 to 50, for example.

System B
Hangs with r1106. No hangs with ftdi_set_latency_timer(1) but problems begin with latency 5.

System C
Even sporadic hangs with ftdi_set_latency_timer(1).

Several solutions were already tested (refer to thread [UrJTAG-dev] Sometimes detect command hangs).

[Arnim Läuger]

Logged In: YES
user_id=156321
Originator: YES

Problems on system A could be resolved with an experimental patch against libftdi-0.10 (see mailing list thread). Didn't resolve issue with systems B and/or C.

[Arnim Läuger]

Logged In: YES
user_id=156321
Originator: YES

Enhanced the init sequence in ftdi.c to fix the hangs seen with a laptop. The sequence contains also additional commands that are disabled yet and might get enabled in the future if libftdi is updated accordingly.

[Arnim Läuger]

Logged In: YES
user_id=156321
Originator: YES

This issue doesn't occur anymore with r1354 on systems I have access to.