refine xhci-plat-Fix-xhci_plat-shutdown-sequence

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Apr 17, 2018 at 11:32:42AM +0800, leiwan@codeaurora.org wrote:
> 
> xhci-plat Shutdown callback should check HCD_FLAG_HW_ACCESSIBLE
> before accessing any register. This should avoid hung with access
> controllers which support runtime suspend
> 
> This can fix for issue of https://patchwork.kernel.org/patch/10339317/
> corresponding upload in CAF:
> https://source.codeaurora.org/quic/la/kernel/msm-4.4/commit/?h=LV.HB.1.1.5-03810-8x96.0&id=a7a5307ee04ad349d365ad50f304605a9cd9bd0a
> 
> full patch refer attachment.
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 9b27798..bdf914d 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -702,6 +702,10 @@ static void xhci_shutdown(struct usb_hcd *hcd)
>                 usb_disable_xhci_ports(to_pci_dev(hcd->self.sysdev));
> 
>         spin_lock_irq(&xhci->lock);
> +       if (!HCD_HW_ACCESSIBLE(hcd)) {
> +               spin_unlock_irq(&xhci->lock);
> +               return;
> +       }
>         xhci_halt(xhci);

A blank line after the if statement?

What about all of the other places in this driver that you should also
check for this?  Look at the other host controllers, shouldn't you
mirror what they are doing?

And this needs a Fixes: tag, along with a cc: stable so as to properly
get backported as this is broken in some stable kernels right now.

thanks,

greg k-h
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