Re: [PATCH] usb: host: xhci: Fix Compliance Mode on SN65LVPE502CP Hardware

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jul 31, 2012 at 05:48:38PM -0500, Alexis R. Cortes wrote:
> This patch is intended to work around a known issue on the
> SN65LVPE502CP USB3.0 re-driver that can delay the negotiation
> between a device and the host past the usual handshake timeout,
> and if that happens on the first insertion, the host controller
> port will enter in Compliance Mode as per xHCI Spec. The patch
> creates a timer which polls every 2 seconds the link state of each
> host controller's port (this by reading the PORTSC register) and
> recovers the port by issuing a Warm reset every time Compliance mode
> is detected.
> 
> Signed-off-by: Alexis R. Cortes <alexis.cortes@ti.com>
> ---
>  drivers/usb/host/xhci-hub.c |   27 ++++++++++++++
>  drivers/usb/host/xhci.c     |   81 +++++++++++++++++++++++++++++++++++++++++++
>  drivers/usb/host/xhci.h     |    6 +++
>  3 files changed, 114 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
> index 7b01094..4ea498d 100644
> --- a/drivers/usb/host/xhci-hub.c
> +++ b/drivers/usb/host/xhci-hub.c
> @@ -493,7 +493,19 @@ static void xhci_hub_report_link_state(u32 *status, u32 status_reg)
>  		 * when this bit is set.
>  		 */
>  		pls |= USB_PORT_STAT_CONNECTION;
> +	} else {
> +		/*
> +		 * If CAS bit isn't set but the Port is already at
> +		 * Compliance Mode, fake a connection so the USB core
> +		 * notices the Compliance state and resets the port.
> +		 * This resolves an issue generated by the SN65LVPE502CP
> +		 * in which sometimes the port enters compliance mode
> +		 * caused by a delay on the host-device negotiation.
> +		 */
> +		if (pls == USB_SS_PORT_LS_COMP_MOD)
> +			pls |= USB_PORT_STAT_CONNECTION;
>  	}
> +
>  	/* update status field */
>  	*status |= pls;
>  }
> @@ -645,6 +657,21 @@ int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
>  		/* Update Port Link State for super speed ports*/
>  		if (hcd->speed == HCD_USB3) {
>  			xhci_hub_report_link_state(&status, temp);
> +			/*
> +			 * Verify if all USB3 Ports Have entered U0. Delete compliance
> +			 * mode timer if so.
> +			 */
> +			if (xhci->quirks & XHCI_COMP_MODE_QUIRK) {
> +				if (xhci->port_status_u0 != ((1 << xhci->num_usb3_ports)-1)) {
> +					if ((temp & PORT_PLS_MASK) == XDEV_U0)
> +						xhci->port_status_u0 |= 1 << wIndex;
> +				} else {
> +					/* Deleting Compliance Mode Recovery Timer */
> +					if (del_timer_sync(&xhci->comp_mode_recovery_timer))
> +						xhci_dbg(xhci, "Compliance Mode Recovery Timer Deleted. "
> +							       "All USB3 ports have entered U0 at least once.\n");

You need to disable the quirk flag here now, right?  Otherwise can't the
timer be deleted twice if the module is unloaded after this happens?

thanks,

greg k-h