linux-kernel - Re: 5.16.0-rc7+ Bluetooth error

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Date:   Sat, 1 Jan 2022 13:20:43 +0000
From:   Chris Clayton <chris2553@...glemail.com>
To:     Luiz Augusto von Dentz <luiz.dentz@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
        Kiran K <kiran.k@...el.com>
Subject: Re: 5.16.0-rc7+ Bluetooth error



On 01/01/2022 11:03, Chris Clayton wrote:
> 
> 
> On 31/12/2021 19:53, Luiz Augusto von Dentz wrote:
>> Hi Chris,
>>
>> On Fri, Dec 31, 2021 at 2:35 AM Chris Clayton <chris2553@...glemail.com> wrote:
>>>
>>> On 30/12/2021 09:21, Chris Clayton wrote:
>>>> Hi,
>>>>
>>>> I pulled the latest changes into my clone of Linus' tree and built and installed the kernel. (git describe gives
>>>> v5.16-rc7-9-ge7c124bd0463). I'm seeing errors reported by the bluetooth subsystem that i don't see in 5.15.12 or 5.10.89
>>>>
>>>> The problem seems to occur twice during system startup and on each occasion I see a batch of identical error messages:
>>>>
>>>> [    3.980822] Bluetooth: hci0: Failed to read codec capabilities (-56)
>>>> [    3.982812] Bluetooth: hci0: Failed to read codec capabilities (-56)
>>>> [    3.984812] Bluetooth: hci0: Failed to read codec capabilities (-56)
>>>> [    3.986608] Bluetooth: hci0: Failed to read codec capabilities (-56)
>>>> [    3.987621] Bluetooth: hci0: Failed to read codec capabilities (-56)
>>>> [    3.988606] Bluetooth: hci0: Failed to read codec capabilities (-56)
>>>> [    3.989650] Bluetooth: hci0: Failed to read codec capabilities (-56)
>>>>
>>>
>>> Sorry, I should have said that despite the above errors, my bluetooth devices still work fine.
>>
>> Would be great to have the HCI trace (btmon).
>>
> 
> How would I go about capturing that, please? This all happens during boot, so I don't have access to the system to set
> up a trace.
> 

I thought about this a bit more and realised that one batch of the errors messages occurs when the bluetooth service is
being started in userspace. Si I stopped that service, started btmon and restarted the service.  The trace is attached.

The error messages I am seeing seem to coincide with the "Status: Unknown HCI Command (0x01)" messages that are in the
trace. The first instance of that is at line 951 of the trace.


> 
>> @Kiran K Is this to be expected?
>>
>>>
>>>> A full dmesg log is attached. I've also attached Two files containing the output from "lsusb -v" run on 5.10.89 and
>>>> 5.16-rc7.
>>>>
>>>> Please let me know if I can provide any other diagnostic information or test any patches. You'll need to cc me on
>>>> replies because I'm not subscribed to LKML or linux-bluetooth.
>>>>
>>>> Thanks
>>
>>
>>
View attachment "hcitrace.txt" of type "text/plain" (61440 bytes)