usb: host: xhci: Fix Compliance Mode on SN65LVPE502CP Hardware

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.

If that happens on the first insertion, the host controller
port will enter in Compliance Mode and NO port status event will
be generated (as per xHCI Spec) making impossible to detect this
event by software. The port will remain in compliance mode until
a warm reset is applied to it.

As a result of this, the port will seem "dead" to the user and no
device connections or disconnections will be detected.

For solving this, 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.

If a xHC USB3.0 port has previously entered to U0, the compliance
mode issue will NOT occur only until system resumes from
sleep/hibernate, therefore, the compliance mode timer is stopped
when all xHC USB 3.0 ports have entered U0. The timer is initialized
again after each system resume.

Since the issue is being caused by a piece of hardware, the timer
will be enabled ONLY on those systems that have the SN65LVPE502CP
installed (this patch uses DMI strings for detecting those systems)
therefore making this patch to act as a quirk (XHCI_COMP_MODE_QUIRK
has been added to the xhci stack).

This patch applies for these systems:
Vendor: Hewlett-Packard. System Models: Z420, Z620 and Z820.

This patch should be backported to kernels as old as 3.2, as that was
the first kernel to support warm reset.  The kernels will need to
contain both commit 10d674a82e553cb8a1f41027bb3c3e309b3f6804 "USB: When
hot reset for USB3 fails, try warm reset" and commit
8bea2bd37df08aaa599aa361a9f8b836ba98e554 "usb: Add support for root hub
port status CAS".  The first patch add warm reset support, and the
second patch modifies the USB core to issue a warm reset when the port
is in compliance mode.

Signed-off-by: Alexis R. Cortes <alexis.cortes@ti.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

1 files changed, 42 insertions, 0 deletions

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 74bfc868b7ad..d5eb357aa5c4 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -493,11 +493,48 @@ 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;
 }
 
+/*
+ * Function for Compliance Mode Quirk.
+ *
+ * This Function verifies if all xhc USB3 ports have entered U0, if so,
+ * the compliance mode timer is deleted. A port won't enter
+ * compliance mode if it has previously entered U0.
+ */
+void xhci_del_comp_mod_timer(struct xhci_hcd *xhci, u32 status, u16 wIndex)
+{
+	u32 all_ports_seen_u0 = ((1 << xhci->num_usb3_ports)-1);
+	bool port_in_u0 = ((status & PORT_PLS_MASK) == XDEV_U0);
+
+	if (!(xhci->quirks & XHCI_COMP_MODE_QUIRK))
+		return;
+
+	if ((xhci->port_status_u0 != all_ports_seen_u0) && port_in_u0) {
+		xhci->port_status_u0 |= 1 << wIndex;
+		if (xhci->port_status_u0 == all_ports_seen_u0) {
+			del_timer_sync(&xhci->comp_mode_recovery_timer);
+			xhci_dbg(xhci, "All USB3 ports have entered U0 already!\n");
+			xhci_dbg(xhci, "Compliance Mode Recovery Timer Deleted.\n");
+		}
+	}
+}
+
 int xhci_hub_control(struct usb_hcd *hcd, u16 typeReq, u16 wValue,
 		u16 wIndex, char *buf, u16 wLength)
 {
@@ -651,6 +688,11 @@ 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 already.
+			 * Delete Compliance Mode Timer if so.
+			 */
+			xhci_del_comp_mod_timer(xhci, temp, wIndex);
 		}
 		if (bus_state->port_c_suspend & (1 << wIndex))
 			status |= 1 << USB_PORT_FEAT_C_SUSPEND;