We're loosing serial bytes from PC to phone

Hi! It seems we're loosing serial characters on their way from the (Linux) PC to the phone. I think I've seen this at some point in the past, but now I'm seeing it constantly. Let's assume we're trying to send the following sequence of bytes from the PC side to the phone in one of the HLDC connections: what we actually get from the sercomm callback on the phone is: as you can see, there is a '00 01' missing between the '00' and the '02'. Interestingly, putting a usleep(10000) after every serial write does not solve the problem, so it is not timing related. We don't get any UART overflows on the calypso, either. If I change the data pattern, then the first bytes are transmitted fine, but as soon as there is one 00 bytes, two characters are missing from the stream. If I strace osmocon, it is clear that we write every character, including the null-bytes, and all of the writes are successfully. I've again looked at (and played with) the termios settings, but could not find any problem (nor solution). It's also not the sercomm layer that is loosing bytes, as I the characters appear already lost when printing them from within the calypso UART driver, as you can see here: getchar_nb(1) = 7e // flag character getchar_nb(1) = 05 // hdlc getchar_nb(1) = 03 // hdlc getchar_nb(1) = 0a // l1ctl_hdr (undefined msg_type 10) getchar_nb(1) = 00 // padding getchar_nb(1) = 02 // here should be 00, 01, 02... getchar_nb(1) = 03 getchar_nb(1) = 04 getchar_nb(1) = 05 [...] Any ideas? It's really strange and I don't really know what else to do. I'm quite sure our binaries contain multiple successive null-bytes and their download is working great... Regards, Harald -- - Harald Welte <laforge(a)gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)