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authorMatthijs Kooijman <matthijs@stdin.nl>2019-06-08 21:50:17 +0200
committerMatthijs Kooijman <matthijs@stdin.nl>2019-06-08 21:50:17 +0200
commitb237dcc8e23abb9e79228e3a175a5286131f9f7a (patch)
tree5d76b60c7236496e8b562b7450edc58ddc0d4842 /libraries/Esplora/examples
parent7a2e1cd815266fef3012a5c9b48f88d78551f838 (diff)
Do not claim AT-protocol in CDC interface descriptor
The CDC code presents itself as a virtual serial port. However, it also sets the "bFunctionProtocol" value to 1, which means it supports AT-commands, which is not actually the case. This might cause problems with some software, such as ModemManager. Originally, ModemManager would be very liberal with probing serial devices, using a blacklist to prevent probing non-modems such as Arduinos. Since version 1.7.990, it has supported a "strict" mode where it tries to be more restrained in what devices it probes. For CDC ACM devices, this means it will only probe devices that claim to support AT-commands. However, it also stopped applying the blacklist (intending to eventually remove the blacklist), meaning it would again probe Arduinos. This new strict policy is not the upstream default, but is enabled in Debian (since Buster) and Ubuntu (since bionic 18.04.2). The proper way to fix this, is to not claim AT comand support in the USB device descriptor, which is what this commit does. The Arduino will still show up as a virtual serial port, just not be probed by ModemManager in strict mode. For the commit that introduced the strict mode in ModemManager, see https://cgit.freedesktop.org/ModemManager/ModemManager/commit/src?id=ee570d44dc117dc69f23e83313dd877f76c5e3e0
Diffstat (limited to 'libraries/Esplora/examples')
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