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From: Marcel Holtmann <marcel@holtmann.org>
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Subject: Fedora 27 kernel and RPi3 Bluetooth oops
Message-Id: <BAA83E9E-B9BF-48AD-9955-20B599AFA52C@holtmann.org>
Date: Mon, 18 Sep 2017 19:14:39 +0200
Cc: Loic Poulain <loic.poulain@gmail.com>,
        Peter Robinson <pbrobinson@gmail.com>
To: linux-bluetooth@vger.kernel.org
Sender: linux-bluetooth-owner@vger.kernel.org
List-ID: <linux-bluetooth.vger.kernel.org>

Hi,

the latest Fedora 27 kernel which has all the RPi3 patches applied doesn’t actually work. It provides this backlog.

[  229.162921] CPU: 1 PID: 582 Comm: kworker/u9:1 Not tainted 4.13.2-300.fc27.armv7hl #1
[  229.171285] Hardware name: Generic DT based system
[  229.176774] Workqueue: hci0 hci_cmd_work [bluetooth]
[  229.176774] Workqueue: hci0 hci_cmd_work [bluetooth]
[  229.182117] [<c0312af4>] (unwind_backtrace) from [<c030d264>] (show_stack+0x18/0x1c)
[  229.190374] [<c030d264>] (show_stack) from [<c0b66174>] (dump_stack+0xa0/0xd8)
[  229.198122] [<c0b66174>] (dump_stack) from [<c03aeaec>] (register_lock_class+0x298/0x514)
[  229.206835] [<c03aeaec>] (register_lock_class) from [<c03b1f9c>] (__lock_acquire+0xe4/0x1608)
[  229.215952] [<c03b1f9c>] (__lock_acquire) from [<c03b3fd0>] (lock_acquire+0x280/0x2dc)
[  229.224386] [<c03b3fd0>] (lock_acquire) from [<c0b80ba4>] (_raw_read_lock+0x4c/0x5c)
[  229.232740] [<c0b80ba4>] (_raw_read_lock) from [<bf47903c>] (hci_uart_tx_wakeup+0x1c/0x98 [hci_uart])
[  229.242725] [<bf47903c>] (hci_uart_tx_wakeup [hci_uart]) from [<bf47a0e0>] (hci_uart_send_frame+0x54/0x6c [hci_uart])
[  229.254485] [<bf47a0e0>] (hci_uart_send_frame [hci_uart]) from [<bf3cb260>] (hci_send_frame+0xc8/0xf4 [bluetooth])
[  229.266157] [<bf3cb260>] (hci_send_frame [bluetooth]) from [<bf3cb334>] (hci_cmd_work+0xa8/0x124 [bluetooth])
[  229.277005] [<bf3cb334>] (hci_cmd_work [bluetooth]) from [<c036f154>] (process_one_work+0x43c/0x83c)
[  229.286689] [<c036f154>] (process_one_work) from [<c0370934>] (worker_thread+0x290/0x40c)
[  229.295355] [<c0370934>] (worker_thread) from [<c0376784>] (kthread+0x14c/0x168)
[  229.303195] [<c0376784>] (kthread) from [<c03080d0>] (ret_from_fork+0x14/0x24)

It results in the first HCI command going through and then every other failing.

= Index Info: 00:00:00:00:00:00 (Broadcom Corporation)
< HCI Command: Broadcom Update UART Baud Rate (0x3f|0x0018) plen 6
        Encoded baud rate: Not used (0x0000)
        Explicit baud rate: 2000000 Mbps
> HCI Event: Command Complete (0x0e) plen 4
      Broadcom Update UART Baud Rate (0x3f|0x0018) ncmd 1
        Status: Success (0x00)
< HCI Command: Reset (0x03|0x0003) plen 0

The HCI Reset command actually times out.

[  231.349802] Bluetooth: hci0 command 0x0c03 tx timeout

What we really need is some kernel specific debug tracing when driver change baud rate etc. to show up in btmon. Drivers need the capability to insert HCI transport level specifics into monitoring interface.

Regards

Marcel