[SRU] [B/D/E/Unstable/OEM-B/OEM-OSP1-B] [PATCH 0/2] Fix unusable USB hub on Dell TB16 after S3

[Kleber Souza]

On 2019-12-11 10:07, Kai-Heng Feng wrote:
> 
> 
>> On Dec 11, 2019, at 17:03, Kleber Souza <kleber.souza at canonical.com> wrote:
>>
>> On 2019-12-05 18:05, Kai-Heng Feng wrote:
>>> BugLink: https://bugs.launchpad.net/bugs/1855312
>>>
>>> [Impact]
>>> Sometimes USB hub on Dell TB16 stop working after S3.
>>>
>>> [Fix]
>>> Attempt to power cycle USB device when a it's stuck at eSS.Disabled
>>> state, it's basically not recoverable. 
>>>
>>> [Test]
>>> After applying the patch, USB ports and USB ethernet are still working
>>> after 100 times S3 stress test.
>>>
>>> [Regression Potential]
>>> Low. This is a last resort attempt, in most cases this code path won't
>>> be reached.
>>>
>>> Kai-Heng Feng (2):
>>>  UBUNTU: SAUCE: USB: core: Make port power cycle a seperate helper
>>>    function
>>>  UBUNTU: SAUCE: USB: core: Attempt power cycle port when it's in
>>>    eSS.Disabled state
>>>
>>> drivers/usb/core/hub.c  | 46 +++++++++++++++++++++++++++++++++++------
>>> drivers/usb/core/hub.h  |  3 +--
>>> drivers/usb/core/port.c |  4 ++--
>>> 3 files changed, 43 insertions(+), 10 deletions(-)
>>>
>>
>> Hi Kai-Heng,
>>
>> The fix is targeted to Unstable so I assume this affects mainline as
>> well. Are we going to try to upstream this fix?
> 
> Yes. I've been poking upstream many times but there's no response.
> This fix is quite crucial to TB16 so we still need this in our kernel.
> 
> Kai-Heng
> 

Although you mentioned this code path is a last resort and won't be executed
in most of the cases, this touches the USB core code and the patches don't 
look trivial. So I would like to get some more info about any regression
tests we have executed on other platforms other than the affected one.

Thanks,
Kleber