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32bit Usage items are not supported by get_usage of libusb backend #454

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#601
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32bit Usage items are not supported by get_usage of libusb backend#454
#601
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bugSomething isn't workinglibusbRelated to libusb backend
@JoergAtGithub

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@JoergAtGithub
JoergAtGithub
opened on Sep 11, 2022

The USB standard allows it to specify a usage in two ways:

  • Fully qualified as one single 4 byte report descriptor Usage item
  • Seperated in an 1 or 2 byte Usage-Page item, followed by an 1 or 2 byte Usage item
    The get_usage function of the libusb backend supports only the second.

From USB HID spec 1.11 page 17:
grafik

From USB HID spec 1.11 page 35:
grafik

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Youw
added
bugSomething isn't working
libusbRelated to libusb backend
on Sep 11, 2022
mcuee

mcuee commented on May 10, 2023

@mcuee
mcuee
on May 10, 2023
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Is it because most of the USB HID Devices use the second way that we have not seen bug report for thr libusb backend?

Youw

Youw commented on May 10, 2023

@Youw
Youw
on May 10, 2023
Member

Yes, likely

Youw
mentioned this on Jul 25, 2023
Youw
closed this as completedin #601on Aug 26, 2023
Youw
added a commit that references this issue on Aug 26, 2023

hidraw: report only Top-Level Usage_page/Usage pairs as 'unique' devi…

8a4de63
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      32bit Usage items are not supported by get_usage of libusb backend · Issue #454 · libusb/hidapi