Attention is currently required from: Hoernchen, laforge, lynxis lazus.
Hoernchen uploaded patch set #2 to this change.
The following approvals got outdated and were removed: Code-Review+1 by laforge, Code-Review+2 by lynxis lazus, Verified+1 by Jenkins Builder
The change is no longer submittable: Code-Review and Verified are unsatisfied now.
firmware: card_emu: use Di in the waiting time
ISO 7816-3 section 10.2 defines WT = WI x 960 x Fi/f seconds,
store as etu, etu = Fi / (D x f) seconds, so the Fi cancels,
but the D does not:
WT [etu] = WI x 960 x D
cemu dropped both (?!) -> WI x 960.
The old comment explains why Fi can be dropped, which is right, but
what about Di ?!
sniffer gets it right (wt_wi * 960UL * wt_d), so the two state machines
disagreed here again, by up to a factor of 64???!!?!!?
This was fixed in osmo-ccid-firmware in 066489d in 2020 but not ported
to st2.
Additionally the waiting time was only recalculated at the end of the ATR,
where D is still 1 by definition, so a PPS increasing D reprogrammed the
baud rate but left the waiting time untouched??!
etu duration shrinks with D by the same factor, wall clock WT is
independent of D, which is the whole point.
The old code decreased the waiting time by a factor of D:
after a PPS to D=8 the card emitted its NULL procedure byte at ~0.09s
instead of ~0.71s with a reader deadline of ~1.43s,
and the inactivity timeout fires 8x too early, which probably led to
unexplained wtime_exp errors.
Update wt when WI becomes known (end of ATR) and
where D changes (after the PPS response) + tests.
Change-Id: I4263176d6073029d01f9ff5b11a6311617956af6
---
M firmware/libcommon/source/card_emu.c
M firmware/test/card_emu_tests.c
2 files changed, 97 insertions(+), 11 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/simtrace2 refs/changes/26/43126/2
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