Re: [PATCH v7 2/2] Bluetooth: qca: Fix BT enable failure for QCA6390 after disable then warm reboot

[Wren Turkal <wt@penguintechs.org>]

On Tuesday, April 23, 2024 9:34:43 PM PDT Greg KH wrote:
> On Wed, Apr 24, 2024 at 12:26:47PM +0800, Zijun Hu wrote:
> > From: Zijun Hu <zijuhu@qti.qualcomm.com>
> > 
> > Commit 272970be3dab ("Bluetooth: hci_qca: Fix driver shutdown on closed
> > serdev") will cause below regression issue:
> > 
> > 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.
> > 
> > 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.
> > 
> > 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.
> > 
> > Fixes: 272970be3dab ("Bluetooth: hci_qca: Fix driver shutdown on closed
> > serdev") Cc: stable@vge.kernel.org
> 
> That is not a valid email address :(

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

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

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

wt
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