[ +CC: Sebastian ] Hi Andreas, and sorry about the late reply on this. On Thu, Jun 06, 2024 at 08:30:28PM +0200, Andreas Kemnade wrote: > Some of these chips have GNSS support. In some vendor kernels > a driver on top of misc/ti-st can be found providing a /dev/tigps > device which speaks the secretive Air Independent Interface (AI2) protocol. Please expand the cover letter and commit messages with more details on the protocols and backstory here. I spent hours over the Christmas break digging through drivers, git logs and mail archives for information that should have been part of the series. Specifically, give a better description of these chips which are WiFi controllers with Bluetooth primarily and then some have (optional?) FM radio and GPS support as well. Some even seem to support NFC too (also over HCI?). Provide some background on the ti-st driver, which have now been removed; the fact that we already had two drivers for these chips with one only supporting the Bluetooth (and later some PM) bits; say something about the FM driver which someone also recently decided to remove on questionable grounds. Please also refer to the prior attempts at adding support for the various subfunctions to the driver (e.g. Sebastian's discussion with Marcel on how to possibly abstract this in Bluetooth core), such as: https://lore.kernel.org/lkml/0C9AD246-B511-4E59-888F-47EAB034D4BF@xxxxxxxxxxxx/ > To be more compatible with userspace send out NMEA by default but > allow a more raw mode by using a module parameter. I'm very hesitant about adding a module parameters for such configuration. There's very little detail about the AI2 protocol in this series, but I'm inclined to just say expose it to user space and let it deal with it. Or you can argue that we'll never be able to reverse engineer the protocol enough, but that enabling NMEA and exposing that is straight-forward enough (and safe) to be done in the kernel. At the least, please provide an overview of the protocol (and also include an example such as the one you provided in a previous thread), what functionality it appears to provide, and how it can be used to generate NMEA (e.g. so we can have a discussion about this). Do all the WiLink devices use AI2? Or could some be exposing raw NMEA? (And how does "TiWi" relate to "WiLink"?) > This was tested on the Epson Moverio BT-200. > > Who will take this series (1-3)? GNSS with ack from Bluetooth? I can take the whole series once we've figured out how to model this. Johan
