Re: [PATCH 3/7] xhci: Don't suspend a xhci usb bus if there is a pending event.

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On Wed, 6 Apr 2016, Mathias Nyman wrote:

> We don't want to runtime suspend a bus if there is an event pending.
> The roothub on a NEC uPD720200 host with a single USB3 device connected
> might go back to runtime suspend immediately after runtime resume as
> hub might not yet see any port changes in resume.
> 
> Prevent this by checking if there is a unhandled event pending when
> calling runtime suspend.
> 
> Cc: <stable@xxxxxxxxxxxxxxx>
> Tested-by: Mike Murdoch <main.haarp@xxxxxxxxx>
> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> ---
>  drivers/usb/host/xhci-hub.c | 6 ++++++
>  drivers/usb/host/xhci.c     | 1 +
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> index d61fcc4..7e8999a 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -1289,12 +1289,18 @@ int xhci_bus_suspend(struct usb_hcd *hcd)
>  	__le32 __iomem **port_array;
>  	struct xhci_bus_state *bus_state;
>  	unsigned long flags;
> +	u32 status;
>  
>  	max_ports = xhci_get_ports(hcd, &port_array);
>  	bus_state = &xhci->bus_state[hcd_index(hcd)];
>  
>  	spin_lock_irqsave(&xhci->lock, flags);
>  
> +	/* Don't suspend root hub if there's an event pending. */
> +	status = readl(&xhci->op_regs->status);
> +	if (status & STS_EINT)
> +		return -EBUSY;

Does anybody else see a problem here?

Alan Stern

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