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From: Werner Sembach <werner@rdorf.de>
To: linux-input@vger.kernel.org
Subject: Need information to implement correct handling of the GSP 370 wireless headset
Date: Fri, 7 Jul 2023 23:12:48 +0200	[thread overview]
Message-ID: <e01dbcd2-3ce3-ebaf-e685-3b89601ae55a@rdorf.de> (raw)

Hi,

The EPOS GSP 370 wireless headset has a volume control knob on the 
headset. Turning this has 2 effects on Linux:

- The volume gets adjusted in firmware

- A volume up/down key event is sent to the OS and the volume is 
adjustet on the OS level (the dongle registers both as a audio device 
and an usb keyboard to do this)

This double volume adjust is ofc not the intended behavior and induces 
all kinds of wiredness, like the os is already displaying 100% volume 
but you can still turn it higher because the firmware has not yet 
reached max volume.

Running Wireshark on Windows and Linux I recognized that Windows is 
sending "URB_CONTROL out" events to the dongle on volume adjust, which 
Linux doesn't, these events have a paylode that seems to encode a volume 
value in 2 byte with little endianess.

I'm unsure if I can attach pcap file or if it will get blocked in the 
list so i will send them as a reply.

So my 2 questions are:

- What are these USB "URB_CONTROL out" events? (Does not seem to be HID 
reports?)

- In which subsystem would I want to implement them? Or should this be 
handled in userspace?

Bast regards,

Werner


             reply	other threads:[~2023-07-07 21:13 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-07-07 21:12 Werner Sembach [this message]
2023-07-07 21:22 ` Need information to implement correct handling of the GSP 370 wireless headset Werner Sembach
2023-07-21  2:45   ` Rahul Rameshbabu
2023-07-21  8:50     ` Werner Sembach

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