Re: [PATCH 1/5] usb: xhci: clear stale bandwidth data after hibernation

["Neronin, Niklas" <niklas.neronin@linux.intel.com>]

On 06/10/2026 19.12, Michal Pecio wrote:
> On Tue,  6 Oct 2026 17:24:23 +0200, Niklas Neronin wrote:
>> Controllers using software managed bandwidth accounting maintain
>> periodic endpoint bandwidth information in struct 'xhci_interval_bw_table'.
>>
>> Each root hub port owns a bandwidth table and a list of TT bandwidth
>> domains, where each TT has its own bandwidth table. Virtual devices
>> reference the bandwidth table of their current bandwidth domain through
>> 'bw_table' or 'tt_info'.
>>
>> Historically, resume from S4 re-allocated the entire xHCI driver state,
>> which implicitly cleared all bandwidth accounting data. After the
>> hibernation resume path was optimized to preserve parts of the driver
>> state, virtual devices and TT bandwidth information were freed and
>> recreated, but the root hub bandwidth tables were left intact.
>>
>> As a result, stale bandwidth accounting data could remain in the root
>> hub bandwidth tables across hibernation resume, leading to incorrect
>> bandwidth calculations after devices were rediscovered.
>>
>> Fix this by resetting all software bandwidth accounting state in
>> xhci_rh_bw_cleanup() so that resume starts with a clean bandwidth state.
>> This includes 'xhci->num_active_eps', which must remain consistent with
>> the cleared bandwidth tables.
> 
> If that's the case then it would make sense to put this inside
> xhci_rh_bw_cleanup() rather than xhci_resume(), wouldn't it?
> 

Function xhci_rh_bw_cleanup() handles cleanup of root hub bandwidth states,
while 'num_active_eps' is a controller wide active endpoint counter.
Since it is not part of the per-root-hub bandwidth accounting state,
I left its reset in xhci_resume(). It also lives in struct 'xhci_hcd'
rather than the root-hub bandwidth structures.

I'll adjust the commit message in the next revision.

Thanks,
Niklas