HID: Revert "Revert "HID: Fix logitech-dj: missing Unifying device issue""

This reverts commit 8af6c08830b1ae114d1a8b548b1f8b056e068887.

This patch re-adds the workaround introduced by 596264082f10dd4
which was reverted by 8af6c08830b1ae114.

The original patch 596264 was needed to overcome a situation where
the hid-core would drop incoming reports while probe() was being
executed.

This issue was solved by c849a6143bec520af 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
executed.

Commit a9dd22b730857347 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 8af6c08.

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 dcd9006b1b053c7b1c 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/1194649

Signed-off-by: Nestor Lopez Casado <nlopezcasad@logitech.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/hid/hid-logitech-dj.h b/drivers/hid/hid-logitech-dj.h
index fd28a5e0ca3b..4a4000340ce1 100644
--- a/drivers/hid/hid-logitech-dj.h
+++ b/drivers/hid/hid-logitech-dj.h
@@ -101,6 +101,7 @@ struct dj_receiver_dev {
 	struct work_struct work;
 	struct kfifo notif_fifo;
 	spinlock_t lock;
+	bool querying_devices;
 };
 
 struct dj_device {