Hi Marcel, 2017-09-20 18:22 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. > > who is providing a 3-wire HCI controller firmware for the nRF52? I know with Zephyr and Mynewt you can turn them into a generic HCI controller, but we have not gotten around to add 3-wire support to Zephyr yet. I have written my own implementation according to the Core v5.0 specification. I thought it was more nice to have a 3wire interface rather than h4 since that adds better error checking, automatic resync upon chip reset etc. > > Regards > > Marcel > -- 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
