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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Mon, 28 Feb 2022 11:34:56 -0800
Message-ID: <CABBYNZJQOSZ1fecTRQOX+w8crdiLdr0_tVstgbnyEVq3NaxscQ@mail.gmail.com>
Subject: Re: bug kernel 5.17, qualcom and intel adapters, unable to reliably
 connect to bluetooth devices
To:     Chris Clayton <chris2553@googlemail.com>
Cc:     Chris Murphy <lists@colorremedies.com>,
        Bluetooth <linux-bluetooth@vger.kernel.org>,
        regressions@lists.linux.dev
Content-Type: text/plain; charset="UTF-8"
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Hi Chris,

On Sat, Feb 26, 2022 at 12:04 AM Chris Clayton <chris2553@googlemail.com> wrote:
>
> Hi,
>
> On 24/02/2022 15:16, Luiz Augusto von Dentz wrote:
> >> I'll try another bisection today, but limit its range to changes made in the net/bluetooth directory.
>
> That  bisection has proved very difficult because the bluetooth "service" in kernels at some steps of the bisection were
> completely borked to the extent that blueman's device-manager application wouldn't start and emitted the messages:
>
> blueman-manager 12.00.37 ERROR    Manager:137 on_dbus_name_appeared: Default adapter not found, trying first available.
> blueman-manager 12.00.37 ERROR    Manager:141 on_dbus_name_appeared: No adapter(s) found, exiting
>
> Obviously, I don't know whether the problem I am trying to pinpoint is hiding behind this more fundamental problem with
> the bluetooth "service", so being unable to say whether that kernel was good or bad, I had to skip. There seems to be a
> batch of commits that mean that, whilst the kernel builds okay, hunting down a bluetooth-related problem is not
> possible. Eventually and I cursed and gave up. Whatever was causing this breakage has obviously been fixed.
>
> > Please record the HCI with btmon, it must be producing something since
> > it records even the mgmt commands.
> >
>
> Refreshed by a good night's sleep, I started another bisection (between 5.16 and 5.17-rc1) yesterday morning but this
> time did not limit it to net/bluetooth.  That was going okay until I ran into what I assume is the same batch of borked
> kernels. I've been more persistent this time but have just had a run of 16 steps in which the bluetooth support in the
> kernel is broken so badly that testing bluetooth is not possible. I will push on today, but I've suspended that activity
> to get the hci trace that Luiz has asked for.
>
> Using information from the bisect, I built a kernel that had tested as bad (but not borked). The commit is
> f2b551fad8d8f2ac5e1f810ad595298381e0b0c5. As I've mentioned before, the problem with devices not connecting is
> intermittent - for a given kernel, sometimes a connection works and other times it doesn't. On the first boot of this
> kernel, my bluetooth devices could connect, Attached are 4 files related to this - the output from btmon, and the
> related portions of daemon.log, kern.log and sys.log from /var/log/. Each of the these files is suffixed with ".good".
>
> I then powered down the laptop and booted into the same kernel. This time the bluetooth devices could not connect. Four
> more files are attached for this boot and are suffixed with ".bad". I said in an earlier email that when connection
> fails, there is no output from btmon, so that log is empty. That's still the case, but I guess that fact itself is a
> clue to what the problem might be. What I can add, however, is that if, in that same bad kernel, I unload and then
> reload the btusb module, connections start to work. Maybe that too is a clue. The same unload/load process revives
> bluetooth on a kernel built after a pull of Linus' latest and greatest this morning.
>
> Since I now have a workround, I'm going stop the current bisection that I was doing.  I've done another couple of steps
> this morning and both produced kernels on which I could not test bluetooth and had to tell git bisect to skip. If
> however, I can provide any other diagnostics, please let me know.
>
> Chris

Can you try with the following patch:

https://patchwork.kernel.org/project/bluetooth/patch/20220228173918.524733-1-brian.gix@intel.com/


-- 
Luiz Augusto von Dentz