On Samstag, 5. September 2020 12:25:17 CEST Stefan Seyfried wrote:
(OT, but still might be useful to some...)
Am 04.09.20 um 17:43 schrieb Ludwig Nussel:
It's complicated indeed. Fabian pointed me at https://github.com/u-boot/u-boot/blob/9bfb567e5f1bfe7de8eb41f8c6d00f49d2b9 a426/common/usb_kbd.c#L461 So u-boot doesn't even accept devices with more than one endpoint. This might also explain why I never could input anything to U-Boot and GRUB on my raspis. The keyboard i tried also has some multimedia keys and they appear on a different input device... don't have it handy to check the usb descriptors, but it might certainly explain that failure.
I think you are mixing multiple interfaces and multiple endpoints here. An interface is a set of endpoints, the endpoints forming the data pipes for a single protocol. An interface typically shows up as a single device in Linux. That said, though there is no causal relationship between multiple interfaces and existence of an interrupt OUT endpoint, there may be a tendency of more complex devices to have it. Kind regards, Stefan -- Stefan Brüns / Bergstraße 21 / 52062 Aachen home: +49 241 53809034 mobile: +49 151 50412019