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Subject: Re: [PATCH 0/2] Quirk to enable QCA9377 to discover BLE devices
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20190423072236.24999-1-jprvita@endlessm.com>
Date:   Tue, 23 Apr 2019 18:17:37 +0200
Cc:     Johan Hedberg <johan.hedberg@gmail.com>,
        Balakrishna Godavarthi <bgodavar@codeaurora.org>,
        ytkim@qca.qualcomm.com, "David S. Miller" <davem@davemloft.net>,
        "open list:BLUETOOTH DRIVERS" <linux-bluetooth@vger.kernel.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux@endlessm.com,
        =?utf-8?Q?Jo=C3=A3o_Paulo_Rechi_Vita?= <jprvita@endlessm.com>
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References: <20190423072236.24999-1-jprvita@endlessm.com>
To:     =?utf-8?Q?Jo=C3=A3o_Paulo_Rechi_Vita?= <jprvita@gmail.com>
Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Joao Paulo,

> As reported previously on [1], it is currently not possible to discover
> BLE devices with QCA9377 controllers. When trying to start an active
> scanning procedure with this controller, three commands are queued,
> LE_SET_RANDOM_ADDR, LE_SET_SCAN_PARAM and LE_SET_SCAN_ENABLE. After the
> first command is sent to the controller, a command complete event for it
> is received, and the second command is sent, an extra command complete
> for the first command is received. At this point the kernel sends the
> next command and fails to process the command complete event for the
> LE_SET_SCAN_PARAM command, because when it arrives it does not match the
> last command that was sent. This makes hdev->le_scan_type never be
> updated and the kernel behaves as if a passive scanning procedure was
> being performed, thus no device found events are sent to userspace.
> 
> [1] https://www.spinics.net/lists/linux-bluetooth/msg79102.html
> 
> I have received no replies on the previous report and on further
> attempts to contact the QCA addresses that have submitted Bluetooth
> firmware blobs to linux-firmware upstream. This series avoids the
> problem described above, but I believe ideally the controller should not
> be sending this extra command complete event.
> 
> I'm not 100% sure if the approach taken here is the best way to work
> around this problem in the kernel, as I am not super familiar with the
> HCI layer. I'll be happy to hear suggestions of better approaches.
> 
> Full logs from btmon can be found bellow this message, and the extra
> command complete event can be seen at timestamp 27.420131.

so can we get a fixed firmware from Qualcomm? Or at least some ROM patches for it?

> Best regards,
> 
> João Paulo Rechi Vita (2):
>  Bluetooth: Create new HCI_QUIRK_WAIT_FOR_MATCHING_CC
>  Bluetooth: Set HCI_QUIRK_WAIT_FOR_MATCHING_CC for QCA9377
> 
> drivers/bluetooth/btusb.c        | 9 +++++++++
> include/net/bluetooth/hci.h      | 4 ++++
> include/net/bluetooth/hci_core.h | 1 +
> net/bluetooth/hci_core.c         | 3 +++
> net/bluetooth/hci_event.c        | 4 ++++
> 5 files changed, 21 insertions(+)
> 
> -- 
> 2.20.1
> 
> Bluetooth monitor ver 5.50
> = Note: Linux version 5.0.0+ (x86_64)                                  0.352340
> = Note: Bluetooth subsystem version 2.22                               0.352343
> = New Index: 80:C5:F2:8F:87:84 (Primary,USB,hci0)               [hci0] 0.352344
> = Open Index: 80:C5:F2:8F:87:84                                 [hci0] 0.352345
> = Index Info: 80:C5:F2:8F:87:84 (Qualcomm)                      [hci0] 0.352346
> @ MGMT Open: bluetoothd (privileged) version 1.14             {0x0001} 0.352347
> @ MGMT Open: btmon (privileged) version 1.14                  {0x0002} 0.352366
> @ MGMT Open: btmgmt (privileged) version 1.14                {0x0003} 27.302164
> @ MGMT Command: Start Discovery (0x0023) plen 1       {0x0003} [hci0] 27.302310
>        Address type: 0x06
>          LE Public
>          LE Random
> < HCI Command: LE Set Random Address (0x08|0x0005) plen 6   #1 [hci0] 27.302496
>        Address: 15:60:F2:91:B2:24 (Non-Resolvable)
>> HCI Event: Command Complete (0x0e) plen 4                 #2 [hci0] 27.419117
>      LE Set Random Address (0x08|0x0005) ncmd 1
>        Status: Success (0x00)
> < HCI Command: LE Set Scan Parameters (0x08|0x000b) plen 7  #3 [hci0] 27.419244
>        Type: Active (0x01)
>        Interval: 11.250 msec (0x0012)
>        Window: 11.250 msec (0x0012)
>        Own address type: Random (0x01)
>        Filter policy: Accept all advertisement (0x00)
>> HCI Event: Command Complete (0x0e) plen 4                 #4 [hci0] 27.420131
>      LE Set Random Address (0x08|0x0005) ncmd 1
>        Status: Success (0x00)

so we really need to ignore this command complete and not start ahead with the next command. Especially since we really only support one command at a time right now.

> < HCI Command: LE Set Scan Enable (0x08|0x000c) plen 2      #5 [hci0] 27.420259
>        Scanning: Enabled (0x01)
>        Filter duplicates: Enabled (0x01)
>> HCI Event: Command Complete (0x0e) plen 4                 #6 [hci0] 27.420969
>      LE Set Scan Parameters (0x08|0x000b) ncmd 1
>        Status: Success (0x00)

We need for this command complete to arrive and only then continue with LE Set Scan Enable. We don’t need a quirk for it. Just add support for dealing with unexpected command complete opcodes. And print a big error if that happens.

>> HCI Event: Command Complete (0x0e) plen 4                 #7 [hci0] 27.421983
>      LE Set Scan Enable (0x08|0x000c) ncmd 1
>        Status: Success (0x00)
> @ MGMT Event: Command Complete (0x0001) plen 4        {0x0003} [hci0] 27.422059
>      Start Discovery (0x0023) plen 1
>        Status: Success (0x00)
>        Address type: 0x06
>          LE Public
>          LE Random

Regards

Marcel