[PATCH] xhci: Reset controller on xhci shutdown

[PATCH] xhci: Reset controller on xhci shutdown

[wenxiong]

From: Wen Xiong <wenxiong@linux.ibm.com>

Fixes kexec boot. Without a hard reset, some USB chips will fail to
initialize in a kexec booted kernel.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Wen Xiong <wenxiong@linux.ibm.com>
---
 drivers/usb/host/xhci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index a9e47e178c28..364bd61a4bd7 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -781,6 +781,9 @@ void xhci_shutdown(struct usb_hcd *hcd)
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 			"xhci_shutdown completed - status = %x",
 			readl(&xhci->op_regs->status));
+
+	/* TI XHCI controllers do not come back after kexec without this hack */
+	pci_reset_function_locked(to_pci_dev(hcd->self.sysdev));
 }
 EXPORT_SYMBOL_GPL(xhci_shutdown);
 
-- 
2.52.0

Re: [PATCH] xhci: Reset controller on xhci shutdown

[Mathias Nyman]

Hi

On 10/2/26 01:25, wenxiong@linux.ibm.com wrote:
> From: Wen Xiong <wenxiong@linux.ibm.com>
> 
> Fixes kexec boot. Without a hard reset, some USB chips will fail to
> initialize in a kexec booted kernel.
> 
> Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
> Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> Signed-off-by: Wen Xiong <wenxiong@linux.ibm.com>
> ---
>   drivers/usb/host/xhci.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index a9e47e178c28..364bd61a4bd7 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -781,6 +781,9 @@ void xhci_shutdown(struct usb_hcd *hcd)
>   	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
>   			"xhci_shutdown completed - status = %x",
>   			readl(&xhci->op_regs->status));
> +
> +	/* TI XHCI controllers do not come back after kexec without this hack */
> +	pci_reset_function_locked(to_pci_dev(hcd->self.sysdev));
>   }
>   EXPORT_SYMBOL_GPL(xhci_shutdown);
>   

Should be added to xhci-pci.c: xhci_pci_shutdown() instead.

Probably also limited to that specific TI xHC controller

Thanks
Mathias

Re: [PATCH] xhci: Reset controller on xhci shutdown

[Michal Pecio]

On Thu,  1 Oct 2026 18:25:27 -0400, wenxiong@linux.ibm.com wrote:
> From: Wen Xiong <wenxiong@linux.ibm.com>
> 
> Fixes kexec boot. Without a hard reset, some USB chips will fail to
> initialize in a kexec booted kernel.

What exactly happens after kexec?
Why a PCI reset in particular?
Are we sure it's not a bug elsewhere?

Regards,
Michal