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  • Hans de Goede's avatar
    HID: logitech-hidpp: use RAP instead of FAP to get the protocol version · 09637752
    Hans de Goede authored
    According to the logitech_hidpp_2.0_specification_draft_2012-06-04.pdf doc:
    https://lekensteyn.nl/files/logitech/logitech_hidpp_2.0_specification_draft_2012-06-04.pdf
    
    
    
    We should use a register-access-protocol request using the short input /
    output report ids. This is necessary because 27MHz HID++ receivers have
    a max-packetsize on their HIP++ endpoint of 8, so they cannot support
    long reports. Using a feature-access-protocol request (which is always
    long or very-long) with these will cause a timeout error, followed by
    the hidpp driver treating the device as not being HID++ capable.
    
    This commit fixes this by switching to using a rap request to get the
    protocol version.
    
    Besides being tested with a (046d:c517) 27MHz receiver with various
    27MHz keyboards and mice, this has also been tested to not cause
    regressions on a non-unifying dual-HID++ nano receiver (046d:c534) with
    k270 and m185 HID++-2.0 devices connected and on a unifying/dj receiver
    (046d:c52b) with a HID++-2.0 Logitech Rechargeable Touchpad T650.
    
    Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Signed-off-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
    09637752