On Tue, Jul 7, 2020 at 9:03 AM Marcel Holtmann [off-list ref] wrote:

Hi Vasily,

quoted

Some adapters (e.g. RTL8723CS) advertise that they have more than
2 pages for local ext features, but they don't support any features
declared in these pages. RTL8723CS reports max_page = 2 and declares
support for sync train and secure connection, but it responds with
either garbage or with error in status on corresponding commands.

please send the btmon for this so I can see what the controller is responding.

Here is relevant part:

< HCI Command: Read Local Extend.. (0x04|0x0004) plen 1  #228 [hci0] 6.889869
        Page: 2

HCI Event: Command Complete (0x0e) plen 14             #229 [hci0] 6.890487

      Read Local Extended Features (0x04|0x0004) ncmd 2
        Status: Success (0x00)
        Page: 2/2
        Features: 0x5f 0x03 0x00 0x00 0x00 0x00 0x00 0x00
          Connectionless Slave Broadcast - Master
          Connectionless Slave Broadcast - Slave
          Synchronization Train
          Synchronization Scan
          Inquiry Response Notification Event
          Coarse Clock Adjustment
          Secure Connections (Controller Support)
          Ping
< HCI Command: Delete Stored Lin.. (0x03|0x0012) plen 7  #230 [hci0] 6.890559
        Address: 00:00:00:00:00:00 (OUI 00-00-00)
        Delete all: 0x01

HCI Event: Command Complete (0x0e) plen 6              #231 [hci0] 6.891170

      Delete Stored Link Key (0x03|0x0012) ncmd 2
        Status: Success (0x00)
        Num keys: 0
< HCI Command: Read Synchronizat.. (0x03|0x0077) plen 0  #232 [hci0] 6.891199

HCI Event: Command Complete (0x0e) plen 9              #233 [hci0] 6.891788

      Read Synchronization Train Parameters (0x03|0x0077) ncmd 2
        invalid packet size
        01 ac bd 11 80 80                                ......
= Close Index: 00:E0:4C:23:99:87                              [hci0] 6.891832

hci0 registration stops here and bluetoothctl doesn't even see the controller.

Regards

Marcel