Re: [PATCH] usb: hub: avoid warm port reset during USB3 disconnect

[Mathias Nyman <mathias.nyman@linux.intel.com>]

On 10.12.2021 14.07, Greg KH wrote:
> On Fri, Dec 10, 2021 at 01:16:53PM +0200, Mathias Nyman wrote:
>> During disconnect USB-3 ports often go via SS.Inactive link error state
>> before the missing terminations are noticed, and link finally goes to
>> RxDetect state
>>
>> Avoid immediately warm-resetting ports in SS.Inactive state.
>> Let ports settle for a while and re-read the link status a few times 20ms
>> apart to see if the ports transitions out of SS.Inactive.
>>
>> According to USB 3.x spec 7.5.2, a port in SS.Inactive should
>> automatically check for missing far-end receiver termination every
>> 12 ms (SSInactiveQuietTimeout)
>>
>> The futile multiple warm reset retries of a disconnected device takes
>> a lot of time, also the resetting of a removed devices has caused cases
>> where the reset bit got stuck for a long time on xHCI roothub.
>> This lead to issues in detecting new devices connected to the same port
>> shortly after.
>>
>> Tested-by: Mark Pearson <markpearson@lenovo.com>
>> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
>> ---
>>  drivers/usb/core/hub.c | 24 +++++++++++++++++++-----
>>  1 file changed, 19 insertions(+), 5 deletions(-)
> 
> Does this fix a specific commit, or has it always been this way?  And is

Has been this way for 10 years. A guess would be since kernel v3.0:
5e467f6ebab1 usbcore: warm reset USB3 port in SS.Inactive state
But that code has been altered a few times since then.

> this for 5.16-final or 5.17-rc1 and/or stable trees?

maybe 5.17-rc1. 
Skipping stable until shown to resolve more critical issues, and has been
sitting in upstream for a while.

Thanks
-Mathias