On Wed, 2022-12-07 at 09:58 +0100, Rafael J. Wysocki wrote:
> On Tue, Dec 6, 2022 at 3:58 PM Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>
> wrote:
> >
> > Bastien, Jiri,
> >
> > Commit 532223c8ac57 ("HID: logitech-hidpp: Enable HID++ for all the
> > Logitech
> > Bluetooth devices") caused my Logitech Bluetooth mouse to become
> > unusable.
> >
> > Appended is the change I need to make it work again (note that
> > adding the
> > device ID to unhandled_hidpp_devices[] doesn't help, so there must
> > be some
> > significant enough difference in how the two cases are handled in
> > the stack).
> >
> > Here's what I get in the log without the patch below:
> >
> > [ 36.710574] Bluetooth: HIDP (Human Interface Emulation) ver 1.2
> > [ 36.710592] Bluetooth: HIDP socket layer initialized
> > [ 36.724644] hid-generic 0005:046D:B016.0001: unknown main item
> > tag 0x0
> > [ 36.725860] input: Bluetooth Mouse M336/M337/M535 Mouse as
> > /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-
> > 7:1.0/bluetooth/hci0/hci0:1/0005:046D:B016.0001/input/input14
> > [ 36.728036] input: Bluetooth Mouse M336/M337/M535 Consumer
> > Control as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-
> > 7:1.0/bluetooth/hci0/hci0:1/0005:046D:B016.0001/input/input15
> > [ 36.728823] input: Bluetooth Mouse M336/M337/M535 Keyboard as
> > /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-
> > 7:1.0/bluetooth/hci0/hci0:1/0005:046D:B016.0001/input/input18
> > [ 36.731550] hid-generic 0005:046D:B016.0001: input,hidraw0:
> > BLUETOOTH HID v12.03 Mouse [Bluetooth Mouse M336/M337/M535] on
> > 9c:b6:d0:96:8e:c8
> > [ 36.833039] logitech-hidpp-device 0005:046D:B016.0001: unknown
> > main item tag 0x0
> > [ 36.999064] logitech-hidpp-device 0005:046D:B016.0001: Device
> > not connected
> >
> > and here's what I get with it:
> >
> > [ 43.642546] Bluetooth: HIDP (Human Interface Emulation) ver 1.2
> > [ 43.642559] Bluetooth: HIDP socket layer initialized
> > [ 43.652898] hid-generic 0005:046D:B016.0001: unknown main item
> > tag 0x0
> > [ 43.653833] input: Bluetooth Mouse M336/M337/M535 Mouse as
> > /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-
> > 7:1.0/bluetooth/hci0/hci0:1/0005:046D:B016.0001/input/input14
> > [ 43.655025] input: Bluetooth Mouse M336/M337/M535 Consumer
> > Control as /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-
> > 7:1.0/bluetooth/hci0/hci0:1/0005:046D:B016.0001/input/input15
> > [ 43.655400] input: Bluetooth Mouse M336/M337/M535 Keyboard as
> > /devices/pci0000:00/0000:00:14.0/usb1/1-7/1-
> > 7:1.0/bluetooth/hci0/hci0:1/0005:046D:B016.0001/input/input18
> > [ 43.657521] hid-generic 0005:046D:B016.0001: input,hidraw0:
> > BLUETOOTH HID v12.03 Mouse [Bluetooth Mouse M336/M337/M535] on
> > 9c:b6:d0:96:8e:c8
> >
> > The only difference seems to be that in the former case the
> > logitech-hidpp
> > driver tries to bind to the device, but I guess that is expected.
> > However,
> > when the device ID is added to unhandled_hidpp_devices[], the
> > messages look
> > exactly like in the "good" case, but the mouse still doesn't work.
>
> Here's what happens.
>
> - The logitech-hidpp driver is modular and is not present initially,
> so hid-generic probes first (successfully).
>
> - logitech-hidpp is loaded which causes the device to be reporobed
> due
> to __hid_bus_driver_added().
>
> - Because the ->match() callback in hid-generic returns 0 for the
> device now, it is unbound from the device.
>
> - The probing of logitech-hidpp fails (due to an error in ->probe()).
>
> - The probing of hid-generic fails due to the failing ->match().
>
> So in order for unhandled_hidpp_devices[] in logitech-hidpp to work
> with hid-generic, __check_hid_generic() needs to be amended with a
> change to run the ->match() callback of the "specific" driver being
> tried.
>
> I have a working patch for this that will be sent shortly.
I'm glad my belated questioning of the hid-generic fallback code was
correct ;)
My question about getting the output from the HID++ tool still stands
though.
