core: bump USB spec version in device descriptor to 2.0

[stapelberg]

Description

The Teensy 4.x comes with USB 2.0 support. This change is required to make the device advertise itself as USB 2.0 in the USB device descriptor.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Checklist

• My code follows the code style of this project: C, Python
• I have read the PR Checklist document and have made the appropriate changes.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[drashna]

n

[drashna]

Honestly, I'm not exactly happy with the name for the define, but ... I suck at naming.

Also, could this be documented in: https://github.com/qmk/qmk_firmware/blob/master/docs/config_options.md

[stapelberg]

Sure. Updated the docs.

[fauxpark]

I'm kinda wondering if this even needs a define - all of the MCUs these descriptors currently cover seem to comply with USB 2.0 FS. My previous assumption was this value had to be 1.1 because a USB 2.0 device must also provide a device qualifier descriptor, but I'm now thinking that's only if it is capable of running at high speed and full speed:

https://www.keil.com/pack/doc/mw/USB/html/_u_s_b__device__qualifier__descriptor.html

A high-speed capable device that has different device information for full-speed and high-speed must have a Device Qualifier Descriptor (USB_DEVICE_QUALIFIER_DESCRIPTOR). For example, if the device is currently operating at full-speed, the Device Qualifier returns information about how it would operate at high-speed and vice-versa.

What happens if you define this for, say, an ATmega32U4? If the Windows, macOS and Linux don't complain, I'd say just change it...

[stapelberg]

What happens if you define this for, say, an ATmega32U4

Unfortunately, I don’t have an ATmega32U4 handy. Could you test it, or should we file an issue and address that separately from this change at a later point?

[fauxpark]

Just tried on my Satan, it (and/or Windows) didn't like 2, 1, 0 but 2, 0, 0 seems to work fine.

Some Googling around suggests that 2.10 is not a "real" value, and is what is reported when a USB 3 device is plugged into a USB 2 port. So, that may explain why Windows was confused.

[stapelberg]

Some Googling around suggests that 2.10 is not a "real" value, and is what is reported when a USB 3 device is plugged into a USB 2 port. So, that may explain why Windows was confused.

Ah, yeah, https://community.osr.com/discussion/249588/where-is-the-usb-2-1-specification seems to confirm.

Changed it to 2, 0, 0.

[stapelberg]

Done