Re: [PATCH V3] xhci: Reset TI USB controller on xhci shutdown

Re: [PATCH V3] xhci: Reset TI USB controller on xhci shutdown

[Michal Pecio]

On Wed, 21 Oct 2026 12:06:08 -0400, wenxiong@linux.ibm.com wrote:
> From: Wen Xiong <wenxiong@linux.ibm.com>
> 
> Fixes kexec boot. Without a hard reset, TI pci usb chips will fail to
> initialize in a kexec booted kernel.
> 
> Signed-off-by: Wen Xiong <wenxiong@linux.ibm.com>

[ Adding linux-pci and Bjorn Helgaas ]

I tried to make this code a bit more "proper", by moving the
pci_reset_function_locked() call to xhci-pci.c from xhci.c.

I found that when I actually run this, I get a warning from PCI:

  unlocked secondary bus reset via: __pci_reset_function_locked

Bjorn, any tips what would be a proper way to whack a malfunctioning
PCI device with a heavy hammer to ensure it will work after kexec?
Seems we have pci_reset_function(), which locks the parent bridge for
us, but it also preserves some "state". Do we want that?

I'm also starting to wonder if we shouldn't do this reset after kexec,
to cover for kdump. Or maybe both, because shutdown() is supposed to
quiesce the chip and keep it from doing DMA, and we have no idea what
such chip is doing (if anything) when it refuses to halt.

Thanks,
Michal

> [...]
> +	/*
> +	 * TI xHCI controllers fail to initialize in a kexec
> +	 * kernel without a PCI function reset
> +	 */
> +	if (err && (xhci->quirks & XHCI_RESET_ON_SHUTDOWN))
> +		pci_reset_function_locked(to_pci_dev(hcd->self.sysdev));
> [...]

Re: [PATCH V3] xhci: Reset TI USB controller on xhci shutdown

[Wen Xiong]

> 
> I tried to make this code a bit more "proper", by moving the
> pci_reset_function_locked() call to xhci-pci.c from xhci.c.
> 
> I found that when I actually run this, I get a warning from PCI:
> 
>   unlocked secondary bus reset via: __pci_reset_function_locked
> 

Thanks for your reviewing!
Can we do?
if device is TI/0x8241 device, we just reset it in xhci-pci.c.
We don't need to bother other USB devices.

Thanks,
Wendy
> Bjorn, any tips what would be a proper way to whack a malfunctioning
> PCI device with a heavy hammer to ensure it will work after kexec?
> Seems we have pci_reset_function(), which locks the parent bridge for
> us, but it also preserves some "state". Do we want that?
> 
> I'm also starting to wonder if we shouldn't do this reset after kexec,
> to cover for kdump. Or maybe both, because shutdown() is supposed to
> quiesce the chip and keep it from doing DMA, and we have no idea what
> such chip is doing (if anything) when it refuses to halt.
> 
> Thanks,
> Michal
> 
>> [...]
>> +	/*
>> +	 * TI xHCI controllers fail to initialize in a kexec
>> +	 * kernel without a PCI function reset
>> +	 */
>> +	if (err && (xhci->quirks & XHCI_RESET_ON_SHUTDOWN))
>> +		pci_reset_function_locked(to_pci_dev(hcd->self.sysdev));
>> [...]

Re: [PATCH V3] xhci: Reset TI USB controller on xhci shutdown

[Wen Xiong]

> I tried to make this code a bit more "proper", by moving the
> pci_reset_function_locked() call to xhci-pci.c from xhci.c.
> 
> I found that when I actually run this, I get a warning from PCI:
> 
>   unlocked secondary bus reset via: __pci_reset_function_locked
> 

Hi Michal,

How about we add check TI/failling usb controller in xhci_halt and 
xhci_pci_shutdown?

Thanks,
Wendy
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index a8889081ae82..af6ca5447f22 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -950,6 +950,10 @@ static void xhci_pci_shutdown(struct usb_hcd *hcd)
         /* Yet another workaround for spurious wakeups at shutdown with 
HSW */
         if (xhci->quirks & XHCI_SPURIOUS_WAKEUP)
                 pci_set_power_state(pdev, PCI_D3hot);
+
+       /* TI XHCI controllers do not come back after kexec without this 
hack */
+       if (xhci->quirks & XHCI_HALT_FAIL_TO_RESET)
+               pci_reset_function_locked(pdev);
  }
  
/*-------------------------------------------------------------------------*/
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.cW
index a9e47e178c28..67108692a354 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -120,6 +120,8 @@ void xhci_quiesce(struct xhci_hcd *xhci)
   */
  int xhci_halt(struct xhci_hcd *xhci)
  {
+       struct usb_hcd *hcd = xhci_to_hcd(xhci);
+       struct pci_dev *pdev = to_pci_dev(hcd->self.controller);
         int ret;

         xhci_dbg_trace(xhci, trace_xhci_dbg_init, "// Halt the HC");
@@ -130,6 +132,11 @@ int xhci_halt(struct xhci_hcd *xhci)
         if (ret) {
                 if (!(xhci->xhc_state & XHCI_STATE_DYING))
                         xhci_warn(xhci, "Host halt failed, %d\n", ret);
+
+               if (pdev->vendor == PCI_VENDOR_ID_TI &&
+                               pdev->device == 0x8241)
+                       xhci->quirks |= XHCI_HALT_FAIL_TO_RESET;
+
                 return ret;
         }