• Nestor Lopez Casado's avatar
    HID: Revert "Revert "HID: Fix logitech-dj: missing Unifying device issue"" · ac847139
    Nestor Lopez Casado authored
    commit c63e0e370028d7e4033bd40165f18499872b5183 upstream.
    This reverts commit 8af6c088.
    This patch re-adds the workaround introduced by 59626408
    which was reverted by 8af6c088.
    The original patch 596264 was needed to overcome a situation where
    the hid-core would drop incoming reports while probe() was being
    This issue was solved by c849a614 which added
    hid_device_io_start() and hid_device_io_stop() that enable a specific
    hid driver to opt-in for input reports while its probe() is being
    Commit a9dd22b7 modified hid-logitech-dj so as to use the
    functionality added to hid-core. Having done that, workaround 596264
    was no longer necessary and was reverted by 8af6c088.
    We now encounter a different problem that ends up 'again' thwarting
    the Unifying receiver enumeration. The problem is time and usb controller
    dependent. Ocasionally the reports sent to the usb receiver to start
    the paired devices enumeration fail with -EPIPE and the receiver never
    gets to enumerate the paired devices.
    With dcd9006b the problem was "hidden" as the call to the usb
    driver became asynchronous and none was catching the error from the
    failing URB.
    As the root cause for this failing SET_REPORT is not understood yet,
    -possibly a race on the usb controller drivers or a problem with the
    Unifying receiver- reintroducing this workaround solves the problem.
    Overall what this workaround does is: If an input report from an
    unknown device is received, then a (re)enumeration is performed.
    related bug:
    https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1194649Signed-off-by: default avatarNestor Lopez Casado <nlopezcasad@logitech.com>
    Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
hid-logitech-dj.h 3.45 KB