I am using a YubiKey 5 NFC with GnuPG via PC/SC. I have added `disable-ccid` to `scdaemon.conf` (to avoid conflicting with `pcscd`, based on https://bugs.debian.org/854005 https://github.com/LudovicRousseau/PCSC/issues/65 and https://ludovicrousseau.blogspot.com/2019/06/gnupg-and-pcsc-conflicts.html ). With the YubiKey inserted (as shown by `pcsc_scan`) `gpg --card-status` prints:
gpg: selecting card failed: No such device
gpg: OpenPGP card not available: No such device
With `debug-level expert`, scdaemon logs:
2020-07-16 16:53:22 scdaemon[5479] listening on socket '/run/user/1000/gnupg/S.scdaemon'
2020-07-16 16:53:22 scdaemon[5479] handler for fd -1 started
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 -> OK GNU Privacy Guard's Smartcard server ready
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 <- GETINFO socket_name
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 -> D /run/user/1000/gnupg/S.scdaemon
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 -> OK
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 <- OPTION event-signal=12
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 -> OK
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 <- GETINFO version
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 -> D 2.2.20
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 -> OK
2020-07-16 16:53:22 scdaemon[5479] DBG: chan_7 <- SERIALNO
2020-07-16 16:53:23 scdaemon[5479] detected reader 'Lenovo Integrated Smart Card Reader 00 00'
2020-07-16 16:53:23 scdaemon[5479] detected reader 'Yubico YubiKey FIDO+CCID 01 00'
2020-07-16 16:53:23 scdaemon[5479] detected reader ''
2020-07-16 16:53:23 scdaemon[5479] reader slot 0: not connected
2020-07-16 16:53:23 scdaemon[5479] reader slot 0: not connected
2020-07-16 16:53:23 scdaemon[5479] DBG: chan_7 -> ERR 100696144 No such device <SCD>
2020-07-16 16:53:23 scdaemon[5479] DBG: chan_7 <- RESTART
2020-07-16 16:53:23 scdaemon[5479] DBG: chan_7 -> OK
After many hours of investigating, I was able to make the card work by adding `reader-port Yubico YubiKey FIDO+CCID` to `scdaemon.conf`. To save those hours for future users, I suggest that scdaemon not require `reader-port` for PC/SC when only one card is inserted (and for parity with the built-in CCID driver, which works for me without `reader-port`). If that is not possible, I would suggest the scdaemon output and log give some indication that `reader-port` is required to resolve the `No such device`/`not connected' error, which was not apparent to me.
Thanks for considering,
Kevin