Re: Operating central and peripheral roles concurrently

[Martin Townsend <mtownsend1973@gmail.com>]

On Thu, Nov 15, 2018 at 4:54 PM Martin Townsend <mtownsend1973@gmail.com> wrote:
>
> On Tue, Nov 13, 2018 at 11:21 AM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Emil, Martin,
> > On Tue, Nov 13, 2018 at 12:47 PM Emil Lenngren <emil.lenngren@gmail.com> wrote:
> > >
> > > Hi,
> > >
> > > Den mån 12 nov. 2018 kl 17:19 skrev Martin Townsend <mtownsend1973@gmail.com>:
> > > > I've just been reading the 4.1 spec on GAP and on page 224 it states:
> > > >
> > > >
> > > > "In LE, GAP defines four specific roles: Broadcaster, Observer, Peripheral, and
> > > > Central. A device may support multiple LE GAP roles provided that the underly-
> > > > ing Controller supports those roles or role combinations. However, only one LE
> > > > GAP role may be supported at a given time. Each role specifies the require-
> > > > ments for the underlying Controller. This allows for Controllers to be optimized
> > > > for specific use cases."
> > > >
> > > > Now to me that says a device can support being a central and
> > > > peripheral but doesn't have to support them concurrently so I'm
> > > > guessing if the device is in the peripheral role and then wanted to
> > > > connect to another device you would have to stop being a peripheral
> > > > (ie drop this connection) and then become a central, make the
> > > > connection and when finished disconnect and become a peripheral again
> > > > and wait for the other devices to reconnect to you.  Or am I
> > > > mis-reading this?
> > >
> > > This restriction is lifted in newer versions of the spec. The same
> > > section in version 4.2 says this:
> > > "In LE, GAP defines four specific roles: Broadcaster, Observer, Peripheral, and
> > > Central. A device may support multiple LE GAP roles provided that the
> > > underlying Controller supports those roles or role combinations. Each role
> > > specifies the requirements for the underlying Controller. This allows for
> > > Controllers to be optimized for specific use cases."
> > >
> > > If you use the btmon tool you can easily see what combination of
> > > supported states the controller supports. If you have btmon running
> > > while you initiate bluetoothd you will see the packet LE Read
> > > Supported States Command, which contains this info.
> >
> > In that case we should definitely use these states to determine
> > instead of assuming the controller don't support Master & Slave state,
> > though it would be great if Martin provides the HCI traces where it is
> > failing and if indeed is the controller not support it or some other
> > bug.
> >
> > --
> > Luiz Augusto von Dentz
>
> Apologies for the delay.  I've heard back from the device manufacture
> and they have confirmed that it does support both roles simultaneously
> and have proved this using their WICED platform.
> https://community.cypress.com/thread/36729
>
> So I have ran btmon and then powered the device and get the following
> LE Read Supported States message in the log (let me know if you want
> the full log or other messages, there were quite a few of them)
>
> < HCI Command: LE Read Supported States (0x08|0x001c) plen 0
>                            #27 [hci0] 12.173109
> > HCI Event: Command Complete (0x0e) plen 12                                                      #28 [hci0] 12.178836
>       LE Read Supported States (0x08|0x001c) ncmd 1
>         Status: Success (0x00)
>         States: 0x000003ffffffffff
>           Non-connectable Advertising State
>           Scannable Advertising State
>           Connectable Advertising State
>           High Duty Cycle Directed Advertising State
>           Passive Scanning State
>           Active Scanning State
>           Initiating State
>             and Connection State (Master Role)
>           Connection State (Slave Role)
>           Non-connectable Advertising State
>             and Passive Scanning State
>           Scannable Advertising State
>             and Passive Scanning State
>           Connectable Advertising State
>             and Passive Scanning State
>           High Duty Cycle Directed Advertising State
>             and Passive Scanning State
>           Non-connectable Advertising State
>             and Active Scanning State
>           Scannable Advertising State
>             and Active Scanning State
>           Connectable Advertising State
>             and Active Scanning State
>           High Duty Cycle Directed Advertising State
>             and Active Scanning State
>           Non-connectable Advertising State
>             and Initiating State
>           Scannable Advertising State
>             and Initiating State
>           Non-connectable Advertising State
>             and Connection State (Master Role)
>           Scannable Advertising State
>             and Connection State (Master Role)
>           Non-connectable Advertising State
>             and Connection State (Slave Role)
>           Scannable Advertising State
>             and Connection State (Slave Role)
>           Passive Scanning State
>             and Initiating State
>           Active Scanning State
>             and Initiating State
>           Passive Scanning State
>             and Connection State (Master Role)
>           Active Scanning State
>             and Connection State (Master Role)
>           Passive Scanning State
>             and Connection State (Slave Role)
>           Active Scanning State
>             and Connection State (Slave Role)
>           Initiating State
>             and Connection State (Master Role)
>             and Master Role & Master Role
>           Low Duty Cycle Directed Advertising State
>           Low Duty Cycle Directed Advertising State
>             and Passive Scanning State
>           Low Duty Cycle Directed Advertising State
>             and Active Scanning State
>           Connectable Advertising State
>             and Initiating State
>             and Master Role & Slave Role
>           High Duty Cycle Directed Advertising State
>             and Initiating State
>             and Master Role & Slave Role
>           Low Duty Cycle Directed Advertising State
>             and Initiating State
>             and Master Role & Slave Role
>           Connectable Advertising State
>             and Connection State (Master Role)
>             and Master Role & Slave Role
>           High Duty Cycle Directed Advertising State
>             and Connection State (Master Role)
>             and Master Role & Slave Role
>           Low Duty Cycle Directed Advertising State
>             and Connection State (Master Role)
>             and Master Role & Slave Role
>           Connectable Advertising State
>             and Connection State (Slave Role)
>             and Master Role & Slave Role
>           High Duty Cycle Directed Advertising State
>             and Connection State (Slave Role)
>             and Slave Role & Slave Role
>           Low Duty Cycle Directed Advertising State
>             and Connection State (Slave Role)
>             and Slave Role & Slave Role
>           Initiating State
>             and Connection State (Slave Role)
>             and Master Role & Slave Role
>
> Using btmon I then captured the HCI trace for the failing dual role case
>
> Starting the GATT Server and connecting from a PC
> ========================================
> < HCI Command: LE Set Advertising Parameters (0x08|0x0006) plen 15
>                           #69 [hci0] 736.868434
>         Min advertising interval: 1280.000 msec (0x0800)
>         Max advertising interval: 1280.000 msec (0x0800)
>         Type: Connectable undirected - ADV_IND (0x00)
>         Own address type: Public (0x00)
>         Direct address type: Public (0x00)
>         Direct address: 00:00:00:00:00:00 (OUI 00-00-00)
>         Channel map: 37, 38, 39 (0x07)
>         Filter policy: Allow Scan Request from Any, Allow Connect
> Request from Any (0x00)
> > HCI Event: Command Complete (0x0e) plen 4                                                      #70 [hci0] 736.875133
>       LE Set Advertising Parameters (0x08|0x0006) ncmd 1
>         Status: Success (0x00)
> < HCI Command: LE Set Advertise Enable (0x08|0x000a) plen 1
>                           #71 [hci0] 736.878291
>         Advertising: Enabled (0x01)
> > HCI Event: Command Complete (0x0e) plen 4                                                      #72 [hci0] 736.883585
>       LE Set Advertise Enable (0x08|0x000a) ncmd 1
>         Status: Success (0x00)
> @ RAW Close: hciconfig
>                      {0x0004} [hci0] 736.884982
> @ RAW Close: hciconfig
>                             {0x0003} 736.885139
> @ RAW Open: btgatt-server (privileged) version 2.22
>                             {0x0003} 736.950116
> @ RAW Close: btgatt-server
>                             {0x0003} 736.953288
> @ RAW Open: btgatt-server (privileged) version 2.22
>                             {0x0003} 736.953693
> @ RAW Close: btgatt-server
>                             {0x0003} 736.953991
> > HCI Event: LE Meta Event (0x3e) plen 19                                                        #73 [hci0] 752.270109
>       LE Connection Complete (0x01)
>         Status: Success (0x00)
>         Handle: 64
>         Role: Slave (0x01)
>         Peer address type: Public (0x00)
>         Peer address: 9C:B6:D0:DE:5C:A2 (OUI 9C-B6-D0)
>         Connection interval: 45.00 msec (0x0024)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
>         Master clock accuracy: 0x00
> @ MGMT Event: Device Connected (0x000b) plen 13
>                      {0x0001} [hci0] 752.270401
>         LE Address: 9C:B6:D0:DE:5C:A2 (OUI 9C-B6-D0)
>         Flags: 0x00000000
>         Data length: 0
> @ MGMT Event: Device Connected (0x000b) plen 13
>                      {0x0002} [hci0] 752.270401
>         LE Address: 9C:B6:D0:DE:5C:A2 (OUI 9C-B6-D0)
>         Flags: 0x00000000
>         Data length: 0
> < HCI Command: LE Read Remote Used Features (0x08|0x0016) plen 2
>                           #74 [hci0] 752.276167
>         Handle: 64
> > HCI Event: Command Status (0x0f) plen 4                                                        #75 [hci0] 752.281522
>       LE Read Remote Used Features (0x08|0x0016) ncmd 1
>         Status: Success (0x00)
> > HCI Event: LE Meta Event (0x3e) plen 12                                                        #76 [hci0] 752.522510
>       LE Read Remote Used Features (0x04)
>         Status: Success (0x00)
>         Handle: 64
>         Features: 0x1f 0x00 0x00 0x00 0x00 0x00 0x00 0x00
>           LE Encryption
>           Connection Parameter Request Procedure
>           Extended Reject Indication
>           Slave-initiated Features Exchange
>           LE Ping
> < ACL Data TX: Handle 64 flags 0x00 dlen 16
>                           #77 [hci0] 752.522823
>       LE L2CAP: Connection Parameter Update Request (0x12) ident 1 len 8
>         Min interval: 40
>         Max interval: 56
>         Slave latency: 0
>         Timeout multiplier: 42
> > HCI Event: LE Meta Event (0x3e) plen 11                                                        #78 [hci0] 752.612551
>       LE Remote Connection Parameter Request (0x06)
>         Handle: 64
>         Min connection interval: 50.00 msec (0x0028)
>         Max connection interval: 70.00 msec (0x0038)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
> < HCI Command: LE Remote Connection Parameter Request Reply
> (0x08|0x0020) plen 14                #79 [hci0] 752.612732
>         Handle: 64
>         Min connection interval: 50.00 msec (0x0028)
>         Max connection interval: 70.00 msec (0x0038)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
>         Min connection length: 0.000 msec (0x0000)
>         Max connection length: 0.000 msec (0x0000)
> > HCI Event: Command Complete (0x0e) plen 6                                                      #80 [hci0] 752.622017
>       LE Remote Connection Parameter Request Reply (0x08|0x0020) ncmd 1
>         Status: Success (0x00)
>         Handle: 64
> > ACL Data RX: Handle 64 flags 0x02 dlen 10                                                      #81 [hci0] 752.657199
>       LE L2CAP: Connection Parameter Update Response (0x13) ident 1 len 2
>         Result: Connection Parameters accepted (0x0000)
> > HCI Event: Number of Completed Packets (0x13) plen 5                                           #82 [hci0] 752.755860
>         Num handles: 1
>         Handle: 64
>         Count: 1
> > HCI Event: LE Meta Event (0x3e) plen 10                                                        #83 [hci0] 753.017532
>       LE Connection Update Complete (0x03)
>         Status: Success (0x00)
>         Handle: 64
>         Connection interval: 60.00 msec (0x0030)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
>
>
>
> Attempting to connect to another GATT Server (4F:E8:66:0A:92:63)
> ====================================================
> < HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7
>                         #403 [hci0] 1988.511852
>         Type: Passive (0x00)
>         Interval: 60.000 msec (0x0060)
>         Window: 30.000 msec (0x0030)
>         Own address type: Public (0x00)
>         Filter policy: Ignore not in white list (0x01)
> > HCI Event: Ccheck_pending_le_conn: le_num_slave = 1
> ommand Complete (0x0e) plen 4
>           #404 [hci0] 1988.517687
>       LE Set Scan Parameters (0x08|0x000b) ncmd 1
>         Shci_cs_le_create_conn: conn=972bb800
> tatus: Success (0x00)
> < HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
>                         #405 [hci0] 1988.518123
>         Scanning: Enabled (0x01)
>         Filter duplicates: Enabled (0x01)
> > HCI Event: Command Complete (0x0e) plen 4                                                    #406 [hci0] 1988.523477
>       LE Set Scan Enable (0x08|0x000c) ncmd 1
>         Status: Success (0x00)
> > HCI Event: LE Meta Event (0x3e) plen 29                                                      #407 [hci0] 1988.551326
>       LE Advertising Report (0x02)
>         Num reports: 1
>         Event type: Connectable undirected - ADV_IND (0x00)
>         Address type: Random (0x01)
>         Address: 4F:E8:66:0A:92:63 (Resolvable)
>         Data length: 17
>         Flags: 0x02
>           LE General Discoverable Mode
>         Name (complete): LG K8 (2017)
>         RSSI: -71 dBm (0xb9)
> < HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2
>                         #408 [hci0] 1988.557402
>         Scanning: Disabled (0x00)
>         Filter duplicates: Disabled (0x00)
> > HCI Event: Command Complete (0x0e) plen 4                                                    #409 [hci0] 1988.563409
>       LE Set Scan Enable (0x08|0x000c) ncmd 1
>         Status: Success (0x00)
> < HCI Command: LE Create Connection (0x08|0x000d) plen 25
>                         #410 [hci0] 1988.563891
>         Scan interval: 60.000 msec (0x0060)
>         Scan window: 60.000 msec (0x0060)
>         Filter policy: White list is not used (0x00)
>         Peer address type: Random (0x01)
>         Peer address: 4F:E8:66:0A:92:63 (Resolvable)
>         Own address type: Public (0x00)
>         Min connection interval: 50.00 msec (0x0028)
>         Max connection interval: 70.00 msec (0x0038)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
>         Min connection length: 0.000 msec (0x0000)
>         Max connection length: 0.000 msec (0x0000)
> > HCI Event: Command Status (0x0f) plen 4                                                      #411 [hci0] 1988.573442
>       LE Create Connection (0x08|0x000d) ncmd 1
>         Status: Success (0x00)
> > HCI Event: LE Meta Event (0x3e) plen 19                                                      #412 [hci0] 1988.839656
>       LE Connection Complete (0x01)
>         Status: Success (0x00)
>         Handle: 65
>         Role: Master (0x00)
>         Peer address type: Random (0x01)
>         Peer address: 4F:E8:66:0A:92:63 (Resolvable)
>         Connection interval: 60.00 msec (0x0030)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
>         Master clock accuracy: 0x00
> @ MGMT Event: Device Connected (0x000b) plen 30
>                     {0x0001} [hci0] 1988.839788
>         LE Address: 4F:E8:66:0A:92:63 (Resolvable)
>         Flags: 0x00000000
>         Data length: 17
>         Flags: 0x02
>           LE General Discoverable Mode
>         Name (complete): LG K8 (2017)
> @ MGMT Event: Device Connected (0x000b) plen 30
>                     {0x0002} [hci0] 1988.839788
>         LE Address: 4F:E8:66:0A:92:63 (Resolvable)
>         Flags: 0x00000000
>         Data length: 17
>         Flags: 0x02
>           LE General Discoverable Mode
>         Name (complete): LG K8 (2017)
> < HCI Command: LE Read Remote Used Features (0x08|0x0016) plen 2
>                         #413 [hci0] 1988.840257
>         Handle: 65
> > HCI Event: Command Status (0x0f) plen 4                                                      #414 [hci0] 1988.846789
>       LE Read Remote Used Features (0x08|0x0016) ncmd 1
>         Status: Success (0x00)
> > HCI Event: LE Meta Event (0x3e) plen 12                                                      #415 [hci0] 1989.040282
>       LE Read Remote Used Features (0x04)
>         Status: Success (0x00)
>         Handle: 65
>         Features: 0x0f 0x00 0x00 0x00 0x00 0x00 0x00 0x00
>           LE Encryption
>           Connection Parameter Request Procedure
>           Extended Reject Indication
>           Slave-initiated Features Exchange
> > HCI Event: LE Meta Event (0x3e) plen 11                                                      #416 [hci0] 1989.401375
>       LE Remote Connection Parameter Request (0x06)
>         Handle: 65
>         Min connection interval: 7.50 msec (0x0006)
>         Max connection interval: 7.50 msec (0x0006)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 5000 msec (0x01f4)
> < HCI Command: LE Remote Connection Parameter Request Reply
> (0x08|0x0020) plen 14              #417 [hci0] 1989.401742
>         Handle: 65
>         Min connection interval: 7.50 msec (0x0006)
>         Max connection interval: 7.50 msec (0x0006)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 5000 msec (0x01f4)
>         Min connection length: 0.000 msec (0x0000)
>         Max connection length: 0.000 msec (0x0000)
> > HCI Event: Command Complete (0x0e) plen 6                                                    #418 [hci0] 1989.410534
>       LE Remote Connection Parameter Request Reply (0x08|0x0020) ncmd 1
>         Status: Success (0x00)
>         Handle: 65
> > ACL Data RX: Handle 65 flags 0x02 dlen 11                                                    #419 [hci0] 1989.460209
>       ATT: Read By Group Type Request (0x10) len 6
>         Handle range: 0x0001-0xffff
>         Attribute group type: Primary Service (0x2800)
> < ACL Data TX: Handle 65 flags 0x00 dlen 9
>                         #420 [hci0] 1989.461006
>       ATT: Error Response (0x01) len 4
>         Read By Group Type Request (0x10)
>         Handle: 0x0000
>         Error: Request Not Supported (0x06)
> > HCI Event: Number of Completed Packets (0x13) plen 5                                         #421 [hci0] 1989.657151
>         Num handles: 1
>         Handle: 65
>         Count: 1
> > HCI Event: LE Meta Event (0x3e) plen 10                                                      #422 [hci0] 1989.886359
>       LE Connection Update Complete (0x03)
>         Status: Success (0x00)
>         Handle: 65
>         Connection interval: 7.50 msec (0x0006)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 5000 msec (0x01f4)
> > HCI Event: LE Meta Event (0x3e) plen 11                                                      #423 [hci0] 1989.894763
>       LE Remote Connection Parameter Request (0x06)
>         Handle: 65
>         Min connection interval: 60.00 msec (0x0030)
>         Max connection interval: 60.00 msec (0x0030)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
> < HCI Command: LE Remote Connection Parameter Request Reply
> (0x08|0x0020) plen 14              #424 [hci0] 1989.895117
>         Handle: 65
>         Min connection interval: 60.00 msec (0x0030)
>         Max connection interval: 60.00 msec (0x0030)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
>         Min connection length: 0.000 msec (0x0000)
>         Max connection length: 0.000 msec (0x0000)
> > HCI Event: Command Complete (0x0e) plen 6                                                    #425 [hci0] 1989.903898
>       LE Remote Connection Parameter Request Reply (0x08|0x0020) ncmd 1
>         Status: Success (0x00)
>         Handle: 65
> > HCI Event: LE Meta Event (0x3e) plen 10                                                      #426 [hci0] 1989.988169
>       LE Connection Update Complete (0x03)
>         Status: Success (0x00)
>         Handle: 65
>         Connection interval: 60.00 msec (0x0030)
>         Connection latency: 0 (0x0000)
>         Supervision timeout: 420 msec (0x002a)
>
>
> which now seems to be working,  I think maybe the first time I tried
> connecting I didn't specify that the address was a random address for
> the connection to the GATT Server running on my phone using nRF.
>
> I do have this patch in place to remove the check on le_num_slave as
> per the suggestion by Luiz
> @@ -4651,6 +4652,7 @@ static struct hci_conn
> *check_pending_le_conn(struct hci_dev *hdev,
>         struct hci_conn *conn;
>         struct hci_conn_params *params;
>
> +printk(KERN_ERR "%s: le_num_slave = %d\n", __func__,
> hdev->conn_hash.le_num_slave);
>         /* If the event is not connectable don't proceed further */
>         if (adv_type != LE_ADV_IND && adv_type != LE_ADV_DIRECT_IND)
>                 return NULL;
> @@ -4662,8 +4664,10 @@ static struct hci_conn
> *check_pending_le_conn(struct hci_dev *hdev,
>         /* Most controller will fail if we try to create new connections
>          * while we have an existing one in slave role.
>          */
> +#if 0
>         if (hdev->conn_hash.le_num_slave > 0)
>                 return NULL;
> +#endif
>
>         /* If we're not connectable only connect devices that we have in
>          * our pend_le_conns list.
>
> And during the connection I do now see the following in the journal
>
> ov 09 08:57:59 mach-cw-rnet-ppm-1717 kernel: check_pending_le_conn:
> le_num_slave = 1
> Nov 09 08:57:59 mach-cw-rnet-ppm-1717 kernel: hci0 opcode 0x200c plen 2
> Nov 09 08:57:59 mach-cw-rnet-ppm-1717 kernel: skb len 5
>
> which does suggest you were right Luiz.  I'll take the patch out and
> retry the experiment to make sure.
>
> Cheers,
> Martin


I took that patch out and added a printk(KERN_ERR "FAILED CONNECTION
le_num_slave > 0); before returning NULL and it does fail the
connection and I do see the message in the journal:

Nov 09 07:56:23 mach-cw-rnet-ppm-1717 kernel: check_pending_le_conn:
le_num_slave = 1
Nov 09 07:56:23 mach-cw-rnet-ppm-1717 kernel: FAILED CONNECTION le_num_slave > 0