Re: [PATCH] usb: xhci: add xhci_halt() for HCE Handling

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Thu, Feb 26, 2026, Mathias Nyman wrote:
> On 2/26/26 11:27, Dayu Jiang wrote:
> > Hi Greg,
> > 
> > I have updated the changelog text as requested and resubmitted the patch.
> > https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/20260128100746.561626-1-jiangdayu@xiaomi.com/__;!!A4F2R9G_pg!ZSJNDKyOinm26qngopLW-axiQtwDAMely4bDqtqYDGv1ErWCtS6kZ6ZamdiKoZKuCyCk0IxMQK5g625GEIxYWFzKpAEiCUq7$
> > Please kindly review it and let me know if it is acceptable now.
> 
> I'll send it forward, but changed the commit message.
> Does this modified version still describe the case accurately:
> 
> usb: xhci: Prevent interrupt storm on host controller error (HCE)
> 
> The xHCI controller reports a Host Controller Error (HCE) in UAS Storage
> Device plug/unplug scenarios on Android devices, which is checked in
> xhci_irq() function and causes an interrupt storm (since the interrupt
> isn’t cleared), leading to severe system-level faults.
> 
> When the xHC controller reports HCE in the interrupt handler, the driver
> only logs a warning and assumes xHC activity will stop. The interrupt storm
> does however continue until driver manually disables xHC interrupt and
> stops the controller by calling xhci_halt().
> 
> The change is made in xhci_irq() function where STS_HCE status is
> checked, mirroring the existing error handling pattern used for
> STS_FATAL errors.
> 
> This only fixes the interrupt storm. Proper HCE recovery requires resetting
> and re-initializing the xHC.
> 

The controller is halted if there's an error like HCE. It's odd to try
to "halt" it again. Not sure how this will impact for other controllers.
Even if we don't have the full HCE recovery implemented, did we try to
just do HCRST, which is the first step of the recovery?

BR,
Thinh