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From:   Dag Bakke <dag@bakke.com>
Subject: bluez/input/HID keyboard bugs
To:     linux-bluetooth <linux-bluetooth@vger.kernel.org>,
        linux-input@vger.kernel.org
Message-ID: <6ec9eec6-a1fa-7046-8b35-9f014424d4eb@bakke.com>
Date:   Tue, 23 Oct 2018 23:13:52 +0200
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Got myself a bluetooth keyboard. Got issues. More so than
I expected in 2018.

Googling for these issues reveal that they are all problems
seen before, but I am unable to find someone coming up with an actual
explanation or fix for either of them. Nor have I found a public
bugtracker for the userspace side of bluez. 


1. If I press/release CapsLock on the (paired, connected) BT keyboard, 
evbug immediately reports a neverending stream of input. No further 
input from the BT kbd is possible.

tcpdump -i bluetooth0 reports exactly two L2CAP packets in this
scenario.

If I first press/release CapsLock on a connected USB keyboard, the
BT keyboard becomes unresponsive. No further input from
BT is possible.

This is 100% reproducible in my environment.

Making a kernel keymap where CapsLock decodes as VoidSymbol appears 
to work around this problem in the console. A similar workaround for
X11 also "works", until it suddenly doesn't.

I *really* have no clue if this belongs in linux-bluetooth,
linux-input or both.


2. When powering the BT keyboard after having (re)started bluetoothd,
I get the following in the log:

Oct 23 20:23:07 ds81 bluetoothd[7904]: No agent available for request type 0
Oct 23 20:23:07 ds81 bluetoothd[7904]: device_request_pin: Operation not permitted


Now, this keyboard was previously paired and trusted. The link key is present etc.
But it does not connect properly the first time. 
Disconnecting/reconnecting the kbd yeilds:

Oct 23 20:23:43 ds81 kernel: hid-generic 0005:0A5C:8502.001B: unknown main item tag 0x0
Oct 23 20:23:43 ds81 kernel: input: Convertible 2 TKL Keyboard as /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3/1-1.3.2/1-1.3.2:1.0/bluetooth/hci0/hci0:256/0005:0A5C:8502.001B/input/input74
Oct 23 20:23:43 ds81 kernel: evbug: Connected device: input74 (Convertible 2 TKL Keyboard at f8:16:54:64:c6:1a)
Oct 23 20:23:43 ds81 kernel: input: Convertible 2 TKL Consumer Control as /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3/1-1.3.2/1-1.3.2:1.0/bluetooth/hci0/hci0:256/0005:0A5C:8502.001B/input/input75
Oct 23 20:23:43 ds81 kernel: evbug: Connected device: input75 (Convertible 2 TKL Consumer Control at f8:16:54:64:c6:1a)
Oct 23 20:23:43 ds81 kernel: input: Convertible 2 TKL System Control as /devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.3/1-1.3.2/1-1.3.2:1.0/bluetooth/hci0/hci0:256/0005:0A5C:8502.001B/input/input76
Oct 23 20:23:43 ds81 kernel: evbug: Connected device: input76 (Convertible 2 TKL System Control at f8:16:54:64:c6:1a)
Oct 23 20:23:43 ds81 kernel: hid-generic 0005:0A5C:8502.001B: input: BLUETOOTH HID v1.1b Keyboard [Convertible 2 TKL] on f8:16:54:64:c6:1a
Oct 23 20:23:43 ds81 bluetoothd[7904]: No agent available for request type 0
Oct 23 20:23:43 ds81 bluetoothd[7904]: device_request_pin: Operation not permitted


Despite the last two lines in the log, input is now accepted. So it *is* 
possible to make use of a BT keyboard without an agent running all the time.

Can bluetoothd be made to permit a connection at the first attempt as well? 


3. Whenever my BT keyboard goes to sleep or disconnects for any
reason, bluetoothd starts spinning at 100% CPU. And remains doing
so until the keyboard reconnects or bluetoothd is restarted. This is
also 100% reproducible. Makes for noisy fans and unnecessary battery
consumption.

Running bluetoothd -n -d appears to indicate that we're spinning in:

profiles/input/device.c:input_device_enter_reconnect_mode()
path=/org/bluez/hci0/dev_00_18_00_3D_8B_E9 reconnect_mode=device

Running a debug build of bluetoothd through gdb was unsuccessful.
A bit clueless with gdb, sorry.

A previous posting to linux-bluetooth about this particular issue
received no interest. Please let me know what I can do to change this.


Happy to provide more details. 
email works, and I am also in #bluez for the time being.


Thank you,

Dag B


Environment:
PC with kernel 4.19.0-gentoo and bluez 5.50. 
(USB and BT kbd connected at the same time. 
If this is a known problem, does it have to be?)

BT hardware:
Intel 7260 NGW M.2 wifi/bt combo
Filco Convertible 2 TKL keyboard

relevant kernel config options:
CONFIG_BT=y
CONFIG_BT_BREDR=y
CONFIG_BT_RFCOMM=y
CONFIG_BT_RFCOMM_TTY=y
CONFIG_BT_BNEP=y
CONFIG_BT_BNEP_MC_FILTER=y
CONFIG_BT_BNEP_PROTO_FILTER=y
CONFIG_BT_HIDP=y
CONFIG_BT_HS=y
CONFIG_BT_LE=y
CONFIG_BT_INTEL=y
CONFIG_BT_BCM=y
CONFIG_BT_RTL=y
CONFIG_BT_HCIBTUSB=y
CONFIG_BT_HCIBTUSB_BCM=y
CONFIG_BT_HCIBTUSB_RTL=y
CONFIG_HID=y
CONFIG_HID_BATTERY_STRENGTH=y
CONFIG_HID_GENERIC=y
CONFIG_HID_LOGITECH=y
CONFIG_HID_LOGITECH_HIDPP=y
CONFIG_USB_HID=y
CONFIG_HID_PID=y
CONFIG_USB_HIDDEV=y

info from bluetoothd:
Controller F8:16:54:64:C6:1A (public)
        Name: BlueZ 5.50
        Alias: BlueZ 5.50
        Class: 0x00000104
        Powered: yes
        Discoverable: no
        Pairable: yes
        UUID: Generic Attribute Profile
(00001801-0000-1000-8000-00805f9b34fb)
        UUID: A/V Remote Control       
(0000110e-0000-1000-8000-00805f9b34fb)
        UUID: PnP Information          
(00001200-0000-1000-8000-00805f9b34fb)
        UUID: A/V Remote Control Target
(0000110c-0000-1000-8000-00805f9b34fb)
        UUID: Generic Access Profile   
(00001800-0000-1000-8000-00805f9b34fb)
        Modalias: usb:v1D6Bp0246d0532
        Discovering: no

Device 00:18:00:3D:8B:E9 (public)
        Name: Convertible 2 TKL
        Alias: Convertible 2 TKL
        Class: 0x00000540
        Icon: input-keyboard
        Paired: yes
        Trusted: yes
        Blocked: no
        Connected: yes
        LegacyPairing: no
        UUID: Human Interface Device...
(00001124-0000-1000-8000-00805f9b34fb)
        UUID: PnP Information          
(00001200-0000-1000-8000-00805f9b34fb)
        Modalias: usb:v0A5Cp8502d011B