Is your feature request related to a problem? Please describe.
Implementing a HID device which needs to use reports larger than 48 bytes is currently impossible, as btstack hardcodes this value.
You will see something like:
[00:00:30.001] LOG -- l2cap.c.1544: l2cap_send cid 0x43, data length exceeds remote MTU.
Describe the solution you'd like
The MTU values used in hid_device.c should be configurable. Either at build or run time. Runtime seems better, since one may want multiple hid_device instances with different MTUs.
Alternatively, the below mentioned l2cap_create_channel calls could just use the relevant configured max mtu instead of hardcoding 48.
mringwal
commented
1 year ago
Is your feature request related to a problem? Please describe. Implementing a HID device which needs to use reports larger than 48 bytes is currently impossible, as btstack hardcodes this value. You will see something like:
[00:00:30.001] LOG -- l2cap.c.1544: l2cap_send cid 0x43, data length exceeds remote MTU.Describe the solution you'd like The MTU values used in hid_device.c should be configurable. Either at build or run time. Runtime seems better, since one may want multiple hid_device instances with different MTUs. Alternatively, the below mentioned
l2cap_create_channelcalls could just use the relevant configured max mtu instead of hardcoding 48.Additional context The MTUs are currently hardcoded to 48 at these locations: https://github.com/bluekitchen/btstack/blob/ebcec9d303c49e6d6f0b0ef8f3a9efe7abbb14d2/src/classic/hid_device.c#L714 https://github.com/bluekitchen/btstack/blob/ebcec9d303c49e6d6f0b0ef8f3a9efe7abbb14d2/src/classic/hid_device.c#L948