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From: Wren Turkal <wt@penguintechs.org>
To: Zijun Hu <quic_zijuhu@quicinc.com>, linux-bluetooth@vger.kernel.org
Cc: luiz.dentz@gmail.com, luiz.von.dentz@intel.com, marcel@holtmann.org,
 linux-bluetooth@vger.kernel.org, bartosz.golaszewski@linaro.org,
 krzysztof.kozlowski@linaro.org, regressions@lists.linux.dev,
 kernel@quicinc.com, stable@vge.kernel.org,
 Greg KH <gregkh@linuxfoundation.org>
Subject:
 Re: [PATCH v7 2/2] Bluetooth: qca: Fix BT enable failure for QCA6390 after
 disable then warm reboot
Date: Fri, 26 Apr 2024 13:42:33 -0700
Message-ID: <5600892.rdbgypaU67@braindead.localdomain>
In-Reply-To: <2024042330-boat-launch-aaec@gregkh>
References:
 <1713932807-19619-1-git-send-email-quic_zijuhu@quicinc.com>
 <1713932807-19619-3-git-send-email-quic_zijuhu@quicinc.com>
 <2024042330-boat-launch-aaec@gregkh>
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On Tuesday, April 23, 2024 9:34:43=E2=80=AFPM PDT Greg KH wrote:
> On Wed, Apr 24, 2024 at 12:26:47PM +0800, Zijun Hu wrote:
> > From: Zijun Hu <zijuhu@qti.qualcomm.com>
> >=20
> > Commit 272970be3dab ("Bluetooth: hci_qca: Fix driver shutdown on closed
> > serdev") will cause below regression issue:
> >=20
> > BT can't be enabled after below steps:
> > cold boot -> enable BT -> disable BT -> warm reboot -> BT enable failure
> > if property enable-gpios is not configured within DT|ACPI for QCA6390.
> >=20
> > The commit is to fix a use-after-free issue within qca_serdev_shutdown()
> > during reboot, but also introduces this regression issue regarding above
> > steps since the VSC is not sent to reset controller during warm reboot.
> >=20
> > Fixed by sending the VSC to reset controller within qca_serdev_shutdown=
()
> > once BT was ever enabled, and the use-after-free issue is also be fixed
> > by this change since serdev is still opened when send to serdev.
> >=20
> > Fixes: 272970be3dab ("Bluetooth: hci_qca: Fix driver shutdown on closed
> > serdev") Cc: stable@vge.kernel.org
>=20
> That is not a valid email address :(

@ziljun, can you please post this patch in a new patch series by itself? Th=
e=20
warm boot problem is fixed by this patch, and I think it would be better to=
=20
have a thread dedicated to this fix so that it doesn't get lost.

=46WIW, I think that this may be the correct technical change. I would like=
 to=20
try to help get this patch landed, and I think a clean thread for only this=
=20
change would help.

Just so everyone is aware, I am a concerned user of the hardware, and not a=
=20
kernel dev myself. I have tested this change. This patch on top of Linus'=20
mainline does allow qca6390 to work after warm reboot on my laptop.

wt
=2D-=20
You're more amazing than you think!