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

[Kai-Heng Feng]

> On Dec 11, 2019, at 19:16, Kleber Souza <kleber.souza at canonical.com> wrote:
> 
> 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.

Yes I did test on other platforms and didn't observe any regression.

However, I have never seen any other USB device stuck in eSS.Disabled state,
so the code path wasn't executed at all.

Kai-Heng

> 
> Thanks,
> Kleber
>