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

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Date:	Tue, 18 Aug 2015 15:14:14 +0300
From:	Mathias Nyman <mathias.nyman@...el.com>
To:	Roger Quadros <rogerq@...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 18.08.2015 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.

Applied
-Mathias
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