Re: [PATCH 13/17] HID: logitech-hidpp: make .probe usbhid capable

On Wed, 18 Jan 2017, Benjamin Tissoires wrote:

quoted

The current custom solution for the G920 is not the best because
hid_hw_start() is not called at the end of the .probe().
It means that any configuration retrieved after the initial hid_hw_start
would not be exposed to user space without races.

We can simply force hid_hw_start to just enable the transport layer by
not using a connect_mask. This way, we can have a common path between
USB, Unifying and Bluetooth devices.

Tested with a G502 (plain USB), a T650 and many other unifying devices,
and the T651 over Bluetooth.

Signed-off-by: Benjamin Tissoires <redacted>
---
 drivers/hid/hid-logitech-hidpp.c | 88 ++++++++++++++++++++++------------------
 1 file changed, 48 insertions(+), 40 deletions(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index a5d37a4..f5889ff 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c

@@ -2813,6 +2813,17 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
        if (!hidpp_validate_device(hdev))
                return hid_hw_start(hdev, HID_CONNECT_DEFAULT);

+       /*
+        * HID++ needs to read incoming report while in .probe().
+        * However, this doesn't work for plain USB devices until the hdev
+        * status is set with HID_STAT_ADDED (device fully registered once
+        * with HID).
+        * So we ask for it to be reprobed later.
+        */
+       if (id->group != HID_GROUP_LOGITECH_DJ_DEVICE &&
+           !(hdev->status & HID_STAT_ADDED))

Looks like this test breaks the T651 (bluetooth) after all. I seem to
have better success with:
    if (id->bus == BUS_USB && !(hdev->status & HID_STAT_ADDED))

But that also means that the solution will not work if there is only
one USB interface in the device :/

Benjamin,

do you want at least a subset of this patchset to be queued before you 
figure this out, or should I put the whole thing on hold? (not gone 
through it fully yet).

Thanks,

-- 
Jiri Kosina
SUSE Labs