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

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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, thus causing
the port to become Unusable. This 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. Since the issue
is being caused by a pice 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).

Signed-off-by: Alexis R. Cortes <alexis.cortes@xxxxxx>
---
 drivers/usb/host/xhci-hub.c |   28 +++++++++++++++
 drivers/usb/host/xhci.c     |   81 +++++++++++++++++++++++++++++++++++++++++++
 drivers/usb/host/xhci.h     |    6 +++
 3 files changed, 115 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 7b01094..ce4b181 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 +657,22 @@ 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;
+						if (xhci->port_status_u0 == ((1 << xhci->num_usb3_ports)-1)) {
+							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");
+						}
+					}
+				}
+			}
 		}
 		if (bus_state->port_c_suspend & (1 << wIndex))
 			status |= 1 << USB_PORT_FEAT_C_SUSPEND;
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index a979cd0..fea738b 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -26,6 +26,7 @@
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/slab.h>
+#include <linux/dmi.h>
 
 #include "xhci.h"
 
@@ -397,6 +398,62 @@ static void xhci_msix_sync_irqs(struct xhci_hcd *xhci)
 
 #endif
 
+static void compliance_mode_recovery(unsigned long arg)
+{
+	struct xhci_hcd *xhci;
+	struct usb_hcd *hcd;
+	u32 temp;
+	int i;
+
+	xhci = (struct xhci_hcd *)arg;
+
+	for (i = 0; i < xhci->num_usb3_ports; i++) {
+		temp = xhci_readl(xhci, xhci->usb3_ports[i]);
+		if ((temp & PORT_PLS_MASK) == USB_SS_PORT_LS_COMP_MOD) {
+			/* Compliance Mode Detected. Letting USB Core handle the Warm Reset */
+			xhci_dbg(xhci, "Compliance Mode Detected on port %d! Attempting recovery routine.\n", i + 1);
+			hcd = xhci->shared_hcd;
+
+			if (hcd->state == HC_STATE_SUSPENDED)
+				usb_hcd_resume_root_hub(hcd);
+
+			usb_hcd_poll_rh_status(hcd);
+		}
+	}
+
+	if (xhci->port_status_u0 != ((1 << xhci->num_usb3_ports)-1))
+		mod_timer(&xhci->comp_mode_recovery_timer, jiffies + msecs_to_jiffies(COMP_MODE_RCVRY_MSECS));
+}
+
+static void compliance_mode_recovery_timer_init(struct xhci_hcd *xhci)
+{
+	xhci->port_status_u0 = 0;
+	init_timer(&xhci->comp_mode_recovery_timer);
+	xhci->comp_mode_recovery_timer.data = (unsigned long) xhci;
+	xhci->comp_mode_recovery_timer.function = compliance_mode_recovery;
+	xhci->comp_mode_recovery_timer.expires = jiffies + msecs_to_jiffies(COMP_MODE_RCVRY_MSECS);
+	set_timer_slack(&xhci->comp_mode_recovery_timer, msecs_to_jiffies(COMP_MODE_RCVRY_MSECS));
+	add_timer(&xhci->comp_mode_recovery_timer);
+	xhci_dbg(xhci, "Compliance Mode Recovery Timer Initialized.\n");
+}
+
+static bool compliance_mode_recovery_timer_quirk_check(void)
+{
+	const char *dmi_product_name, *dmi_sys_vendor;
+
+	dmi_product_name = dmi_get_system_info(DMI_PRODUCT_NAME);
+	dmi_sys_vendor = dmi_get_system_info(DMI_SYS_VENDOR);
+
+	if (strstr(dmi_sys_vendor, "Hewlett-Packard")) {
+		if (strstr(dmi_product_name, "Z420") || strstr(dmi_product_name, "Z620") ||
+				strstr(dmi_product_name, "Z820")) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
 /*
  * Initialize memory for HCD and xHC (one-time init).
  *
@@ -420,6 +477,12 @@ int xhci_init(struct usb_hcd *hcd)
 	retval = xhci_mem_init(xhci, GFP_KERNEL);
 	xhci_dbg(xhci, "Finished xhci_init\n");
 
+	/* Initializing Compliance Mode Recovery Data If Needed */
+	if (compliance_mode_recovery_timer_quirk_check()) {
+		xhci->quirks |= XHCI_COMP_MODE_QUIRK;
+		compliance_mode_recovery_timer_init(xhci);
+	}
+
 	return retval;
 }
 
@@ -628,6 +691,10 @@ void xhci_stop(struct usb_hcd *hcd)
 	del_timer_sync(&xhci->event_ring_timer);
 #endif
 
+	/* Deleting Compliance Mode Recovery Timer */
+	if ((xhci->quirks & XHCI_COMP_MODE_QUIRK) && (xhci->port_status_u0 != ((1 << xhci->num_usb3_ports)-1)))
+		del_timer_sync(&xhci->comp_mode_recovery_timer);
+
 	if (xhci->quirks & XHCI_AMD_PLL_FIX)
 		usb_amd_dev_put();
 
@@ -802,6 +869,15 @@ int xhci_suspend(struct xhci_hcd *xhci)
 	}
 	spin_unlock_irq(&xhci->lock);
 
+	/*
+	 * Deleting Compliance Mode Recovery Timer because the xHCI Host
+	 * is about to be suspended.
+	 */
+	if ((xhci->quirks & XHCI_COMP_MODE_QUIRK) && (xhci->port_status_u0 != ((1 << xhci->num_usb3_ports)-1))) {
+		del_timer_sync(&xhci->comp_mode_recovery_timer);
+		xhci_dbg(xhci, "Compliance Mode Recovery Timer Deleted - xHC suspended\n");
+	}
+
 	/* step 5: remove core well power */
 	/* synchronize irq when using MSI-X */
 	xhci_msix_sync_irqs(xhci);
@@ -934,6 +1010,11 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
 		usb_hcd_resume_root_hub(hcd);
 		usb_hcd_resume_root_hub(xhci->shared_hcd);
 	}
+
+	/* Initializing Compliance Mode Recovery Timer */
+	if (xhci->quirks & XHCI_COMP_MODE_QUIRK)
+		compliance_mode_recovery_timer_init(xhci);
+
 	return retval;
 }
 #endif	/* CONFIG_PM */
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 55c0785..f1e7874 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1494,6 +1494,7 @@ struct xhci_hcd {
 #define XHCI_TRUST_TX_LENGTH	(1 << 10)
 #define XHCI_LPM_SUPPORT	(1 << 11)
 #define XHCI_INTEL_HOST		(1 << 12)
+#define XHCI_COMP_MODE_QUIRK	(1 << 13)
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
 	/* There are two roothubs to keep track of bus suspend info for */
@@ -1510,6 +1511,11 @@ struct xhci_hcd {
 	unsigned		sw_lpm_support:1;
 	/* support xHCI 1.0 spec USB2 hardware LPM */
 	unsigned		hw_lpm_support:1;
+	/* Compliance Mode Recovery Data */
+	struct timer_list	comp_mode_recovery_timer;
+	u32			port_status_u0;
+/* Compliance Mode Timer Triggered every 2 seconds */
+#define COMP_MODE_RCVRY_MSECS 2000
 };
 
 /* convert between an HCD pointer and the corresponding EHCI_HCD */
-- 
1.7.1

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