tree bbcfbca50545ae12bfd1c7c65eada6b9c003729b
parent f43babac56e2c5ad06e8d9a31170bf220d7f3240
author Harald Welte <laforge@osmocom.org> 1582319224 +0100
committer Harald Welte <laforge@osmocom.org> 1582319385 +0100

client: Work around "stock on PTS" problem

I can occasionally see osmo-remsim-client-st2 get stuck when the Modem
(in this case a Quectel EC20) is performing PTS with the card.

In the log of osmo-remsim-client-st2 I can see:

SIMtrace => PTS req: ff 10 94 7b 00 00
SIMtrace -> 01 07 00 00 00 00 15 00 04 ff 10 94 7b 00 00 ff 10 94 7b
SIMtrace => PTS req: ff 10 94 7b 00 00
SIMtrace IRQ 01 04 00 00 00 00 15 00 13 00 00 00 00 00 09 04 0a 80 25 00 00

after which the communication doesn't proceed. After a long time, the
modem seems to retry without PTS and then proceeds with normal SIM card
communication.

Interestingly, both the firmware and a usbmon trace agree that the first
APDU header after the PTS is actually sent in an USB IN transfer:

-I- 0: computed Fi(1) Di(1) ratio: 372
-I- 0: computed Fi(9) Di(4) ratio: 64
-I- 0: send_tpdu_header: 00 a4 00 04 02
-I- 0: flush_rx_buffer (5)

usbmon shows 010600000000130001000000050000a4000402

It's unclear why the host program doesn't get the data from the IN
transfer.  However, if multiple asynchronous IN EP URB are submited,
the problem can be reproducibly avoided.  Let's do that.

Change-Id: I2fa5f71869b124b73e0c312befce1ca268e9a9a2
Closes: OS#4409