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Message-ID: <e4796a11-7571-b54e-cb82-87bb749709f1@linux.intel.com>
Date: Tue, 5 Apr 2022 18:15:31 +0300
From: Mathias Nyman <mathias.nyman@...ux.intel.com>
To: Henry Lin <henryl@...dia.com>,
Mathias Nyman <mathias.nyman@...el.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xhci: stop polling roothubs after shutdown
On 1.4.2022 14.59, Henry Lin wrote:
> While rebooting, XHCI controller and its bus device will be shut down
> in order by .shutdown callback. Stopping roothubs polling in
> xhci_shutdown() can prevent XHCI driver from accessing port status
> after its bus device shutdown.
>
> Take PCIe XHCI controller as example, if XHCI driver doesn't stop roothubs
> polling, XHCI driver may access PCIe BAR register for port status after
> parent PCIe root port driver is shutdown and cause PCIe bus error.
>
> Signed-off-by: Henry Lin <henryl@...dia.com>
> ---
> drivers/usb/host/xhci.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 2d378543bc3a..e7ae6766220e 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -780,6 +780,14 @@ void xhci_shutdown(struct usb_hcd *hcd)
> if (xhci->quirks & XHCI_SPURIOUS_REBOOT)
> usb_disable_xhci_ports(to_pci_dev(hcd->self.sysdev));
>
> + /* Don't poll the roothubs after shutdown. */
> + xhci_dbg(xhci, "%s: stopping usb%d port polling.\n",
> + __func__, hcd->self.busnum);
> + clear_bit(HCD_FLAG_POLL_RH, &hcd->flags);
> + del_timer_sync(&hcd->rh_timer);
> + clear_bit(HCD_FLAG_POLL_RH, &xhci->shared_hcd->flags);
> + del_timer_sync(&xhci->shared_hcd->rh_timer);
> +
> spin_lock_irq(&xhci->lock);
> xhci_halt(xhci);
> /* Workaround for spurious wakeups at shutdown with HSW */
>
Thanks, adding to queue
-Mathias
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