linux-kernel - Re: [PATCH 4/5] usb: xhci: stop everything on the first call to xhci

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Date:	Thu, 20 Aug 2015 09:42:08 +0300
From:	Roger Quadros <rogerq@...com>
To:	Mathias Nyman <mathias.nyman@...el.com>
CC:	<balbi@...com>, <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/5] usb: xhci: stop everything on the first call to xhci_stop



On 18/08/15 15:14, Mathias Nyman wrote:
> On 18.08.2015 13:39, Roger Quadros wrote:
>> xhci_stop will be called twice, once for the shared hcd
>> and again for the primary hcd.
>>
>> We stop the XHCI controller in any case so clean up
>> everything on the first call else we can timeout
>> waiting for pending requests to complete.
>>
>> Signed-off-by: Roger Quadros <rogerq@...com>
>> ---
>>   drivers/usb/host/xhci.c | 20 +++++---------------
>>   1 file changed, 5 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
>> index d5f44b1..9a7f12c 100644
>> --- a/drivers/usb/host/xhci.c
>> +++ b/drivers/usb/host/xhci.c
>> @@ -655,15 +655,6 @@ int xhci_run(struct usb_hcd *hcd)
>>   }
>>   EXPORT_SYMBOL_GPL(xhci_run);
>>
>> -static void xhci_only_stop_hcd(struct usb_hcd *hcd)
>> -{
>> -    struct xhci_hcd *xhci = hcd_to_xhci(hcd);
>> -
>> -    spin_lock_irq(&xhci->lock);
>> -    xhci_halt(xhci);
>> -    spin_unlock_irq(&xhci->lock);
>> -}
>> -
>>   /*
>>    * Stop xHCI driver.
>>    *
>> @@ -678,15 +669,14 @@ void xhci_stop(struct usb_hcd *hcd)
>>       u32 temp;
>>       struct xhci_hcd *xhci = hcd_to_xhci(hcd);
>>
>> -    mutex_lock(&xhci->mutex);
>> -
>> -    if (!usb_hcd_is_primary_hcd(hcd)) {
>> -        xhci_only_stop_hcd(xhci->shared_hcd);
>> -        mutex_unlock(&xhci->mutex);
>> +    if (xhci->xhc_state & XHCI_STATE_HALTED)
>>           return;
>> -    }
>>
>> +    mutex_lock(&xhci->mutex);
>>       spin_lock_irq(&xhci->lock);
>> +    xhci->xhc_state |= XHCI_STATE_HALTED;
>> +    xhci->cmd_ring_state = CMD_RING_STATE_STOPPED;
>> +
> 
> The XHCI_STATE_HALTED and CMD_RING_STATE_STOPPED states will be set in xhci_halt() right
> after this.
> Well, or,  it actually sets them after waiting for the controller to really halt.
> 
> I guess setting them here helps the second call to hcd_stop() to return early, not taking the mutex and
> trying to stop controller once again.

Yes, that was my intention :)

cheers,
-roger
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