Hi Marcel, 2017-09-20 17:50 GMT+02:00 Marcel Holtmann <marcel@xxxxxxxxxxxx>: > Hi Emil, > >> I'm trying to use the new btattach utility to attach a controller >> which uses the 3-wire UART protocol. The older hciattach works great >> but btattach doesn't. >> This is the command I use including the output: >> >> # btattach -B /dev/ttyS1 -P 3wire -S 500000 >> Attaching Primary controller to /dev/ttyS1 >> Switched line discipline from 0 to 15 >> Failed to get device id: Protocol driver not attached >> No controller attached >> >> By reading the source at >> https://git.kernel.org/pub/scm/bluetooth/bluez.git/tree/tools/btattach.c >> I see that it differs a bit from hciattach. Notably, it calls the >> HCIUARTGETDEVICE ioctl function directly after the HCIUARTSETPROTO >> ioctl call. The hciattach utility does not use HCIUARTGETDEVICE at >> all. >> >> The cause of the problem is that when using 3wire, the hci does not >> get registered immediately (which btattach thinks) but instead after >> the handshake is complete. >> >> If I run btattach in gdb and break before the HCIUARTGETDEVICE ioctl >> call, wait a few seconds and then resume, it works as expected. What >> is the purpose of HCIUARTGETDEVICE? I see it's only being used when >> the Raw option is used (which is by the way not mentioned in the Usage >> docs). >> >> Another issue I have is that hciattach/btattach only support a few >> different baud rates. I want to use 750000 bit/s. Is there a purpose >> of only allowing some? Currently I use hciattach with a dummy baud >> rate followed by >> https://gist.github.com/lategoodbye/f2d76134aa6c404cd92c and that >> works. > > which hardware is this? I always wanted to fix some of the 3-wire support to make sure it fully works with btattach and everything is done inside the kernel correctly. Including proper support for hdev->setup for vendor firmware loading etc. The hardware is an nRF52 device running a generic 3wire implementation. So no custom setup needed here. The 3wire support otherwise in the kernel seems to work very nice as long as I've been testing this. The only thing I miss myself is the lack of the CRC check defined optionally by the 3wire specification. /Emil -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
