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

[leiwan@codeaurora.org]

On 2018-04-17 18:32, Greg KH wrote:
> 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?
>> [lei]I checked other code in this file, seems we do not neeed a blank 
>> line after if here.
> 
> 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?
>> [lei] The issue here is when shutdown called, xhci-host driver will 
>> try to access
>> usb register which may be in runtime suspend state, this lead to a 
>> hang up.
>> Similar as what xhci-host suspend workflow has done, we need check 
>> HW_ACCESS.
> 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.
>> [lei] Added Cc and Fixes part in commit message
> 
> thanks,
> 
> greg k-h


 From c03697fa259ab38d1002598ec2ccfac37607ca0b Mon Sep 17 00:00:00 2001
 From: Lei wang <leiwan@codeaurora.org>
Date: Tue, 17 Apr 2018 10:55:35 +0800
Subject: [PATCH v2] xhci: plat: Fix xhci_plat shutdown hung

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

Fixes: b07c12517f2a ("xhci: plat: Register shutdown for xhci_plat")
Cc: <stable@vger.kernel.org>
Signed-off-by: Lei wang <leiwan@codeaurora.org>
---
  drivers/usb/host/xhci.c | 4 ++++
  1 file changed, 4 insertions(+)

--
1.9.1
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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);
         /* Workaround for spurious wakeups at shutdown with HSW */
         if (xhci->quirks & XHCI_SPURIOUS_WAKEUP)