[PATCH 1/1] UBUNTU: SAUCE: USB: Disable USB2 LPM at shutdown

[Kai-Heng Feng]

at 04:26, Seth Forshee <seth.forshee at canonical.com> wrote:

> On Mon, Jun 10, 2019 at 03:21:41PM +0800, Kai-Heng Feng wrote:
>> BugLink: https://bugs.launchpad.net/bugs/1757218
>>
>> The QCA Rome USB Bluetooth controller has several issues once LPM gets
>> enabled:
>> - Fails to get enumerated in coldboot. [1]
>> - Drains more power (~ 0.2W) when the system is in S5. [2]
>> - Disappears after a warmboot. [2]
>>
>> The issue happens because the device lingers at LPM L1 in S5, so device
>> can't get enumerated even after a reboot.
>>
>> Disable LPM at shutdown to solve the issue.
>>
>> [1] https://bugs.launchpad.net/bugs/1757218
>> [2] https://patchwork.kernel.org/patch/10607097/
>
> On this upstream thread you leak to some doubts are expressed about this
> patch, followed by a promise to dig further into the problem but no
> follow-up. What has transpired since then to verify that this patch is
> 1) safe and 2) not just papering over some other problem?

Alan Stern, one of the USB core supporter, recently gave a positive  
feedback [1] and some minor concerns.
I’ve answered those concerns and I’ll ask Greg KH again to merge the patch.

So 1) it’s safe, 2) the the patch is to solve the root cause, doesn’t paper  
over some other issues.

[1]  
https://lore.kernel.org/linux-usb/Pine.LNX.4.44L0.1906061013490.1641-100000@iolanthe.rowland.org/

Kai-Heng

>
> Thanks,
> Seth