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Date: Wed, 10 Apr 2024 15:00:22 -0700
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Subject: Re: QCA6390 bluetooth doesn't work after warm boot or
 disable/reenable
From: Wren Turkal <wt@penguintechs.org>
To: Luiz Augusto von Dentz <luiz.dentz@gmail.com>,
 Marcel Holtmann <marcel@holtmann.org>,
 Johan Hedberg <johan.hedberg@gmail.com>
Cc: ath11k@lists.infradead.org, linux-bluetooth@vger.kernel.org,
 Kalle Valo <kvalo@kernel.org>
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+Johan since he's a former BT drivers maintainer.

On 4/9/24 1:11 PM, Wren Turkal wrote:
> On 4/9/24 1:03 PM, Luiz Augusto von Dentz wrote:
>> 5.19 seems a little too old, imo, or has it been broken for that long,
>> did you at least tried with bluetooth-next? Try contacting the people
>> who actually wrote the driver.
> 
> Sorry, I didn't answer your question. Yes, I do think it's been broken 
> for longer than that, but I wanted to confirm.

Okay, so I tried 6.9-rc3 and every main release 5.19-6.8.

I have found the following:

* older kernels (6.3 and before) seem to be far less likely to kill on a 
cycling the bluetooth service.
* 6.8/6.9-rcs consistently destroy bluetooth when stopping and 
restarting the service
* If I destroy the bluetooth service with a BT service restart in 
6.9-rc3 and warm reboot into any release back to 5.19, bluetooth does 
not work
* cold boot works in all cases assuming I give the laptop about 5s 
between power off/on

So, I suspsect that the process of closing out the hardware may be 
leaving it in a state that the reset cannot handle (and probably never 
could handle).

I also found that qualcomm has docs here: 
https://www.qualcomm.com/products/technology/wi-fi/fastconnect/fastconnect-6800#Documentation

However, I am not a member of a Qualcomm verified company (mentioned in 
the doc links). Luiz, Marcel, or Johan, do you have any contacts that 
might be able to help me in getting info about the technical docs for 
this hardware? I would love to see if I can find any issues in how the 
hardware is being reset.

As an independent dev, I don't even know what it takes to get that kind 
of access. I would welcome any help here. Hey Qualcomm, are you hiring? :P

wt
-- 
You're more amazing than you think!