linux-kernel - [PATCH 3.12 085/235] xhci: workaround for hosts missing CAS bit

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Message-Id: <9df8806f3366e9e44712c1a45fd7ffa09f28ce30.1485514374.git.jslaby@suse.cz>
Date:   Fri, 27 Jan 2017 11:53:38 +0100
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Mathias Nyman <mathias.nyman@...ux.intel.com>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 085/235] xhci: workaround for hosts missing CAS bit

From: Mathias Nyman <mathias.nyman@...ux.intel.com>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 346e99736c3ce328fd42d678343b70243aca5f36 upstream.

If a device is unplugged and replugged during Sx system suspend
some  Intel xHC hosts will overwrite the CAS (Cold attach status) flag
and no device connection is noticed in resume.

A device in this state can be identified in resume if its link state
is in polling or compliance mode, and the current connect status is 0.
A device in this state needs to be warm reset.

Intel 100/c230 series PCH specification update Doc #332692-006 Errata #8

Observed on Cherryview and Apollolake as they go into compliance mode
if LFPS times out during polling, and re-plugged devices are not
discovered at resume.

Signed-off-by: Mathias Nyman <mathias.nyman@...ux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 drivers/usb/host/xhci-hub.c | 37 +++++++++++++++++++++++++++++++++++++
 drivers/usb/host/xhci-pci.c |  6 ++++++
 drivers/usb/host/xhci.h     |  3 +++
 3 files changed, 46 insertions(+)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 8a79270ca44d..f97a382e3e76 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1221,6 +1221,35 @@ int xhci_bus_suspend(struct usb_hcd *hcd)
 	return 0;
 }
 
+/*
+ * Workaround for missing Cold Attach Status (CAS) if device re-plugged in S3.
+ * warm reset a USB3 device stuck in polling or compliance mode after resume.
+ * See Intel 100/c230 series PCH specification update Doc #332692-006 Errata #8
+ */
+static bool xhci_port_missing_cas_quirk(int port_index,
+					     __le32 __iomem **port_array)
+{
+	u32 portsc;
+
+	portsc = readl(port_array[port_index]);
+
+	/* if any of these are set we are not stuck */
+	if (portsc & (PORT_CONNECT | PORT_CAS))
+		return false;
+
+	if (((portsc & PORT_PLS_MASK) != XDEV_POLLING) &&
+	    ((portsc & PORT_PLS_MASK) != XDEV_COMP_MODE))
+		return false;
+
+	/* clear wakeup/change bits, and do a warm port reset */
+	portsc &= ~(PORT_RWC_BITS | PORT_CEC | PORT_WAKE_BITS);
+	portsc |= PORT_WR;
+	writel(portsc, port_array[port_index]);
+	/* flush write */
+	readl(port_array[port_index]);
+	return true;
+}
+
 int xhci_bus_resume(struct usb_hcd *hcd)
 {
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
@@ -1255,6 +1284,14 @@ int xhci_bus_resume(struct usb_hcd *hcd)
 		int slot_id;
 
 		temp = xhci_readl(xhci, port_array[port_index]);
+
+		/* warm reset CAS limited ports stuck in polling/compliance */
+		if ((xhci->quirks & XHCI_MISSING_CAS) &&
+		    (hcd->speed >= HCD_USB3) &&
+		    xhci_port_missing_cas_quirk(port_index, port_array)) {
+			xhci_dbg(xhci, "reset stuck port %d\n", port_index);
+			continue;
+		}
 		if (DEV_SUPERSPEED(temp))
 			temp &= ~(PORT_RWC_BITS | PORT_CEC | PORT_WAKE_BITS);
 		else
diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 9c3f2c4eaceb..946f63852434 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -43,6 +43,7 @@
 #define PCI_DEVICE_ID_INTEL_SUNRISEPOINT_LP_XHCI	0x9d2f
 #define PCI_DEVICE_ID_INTEL_BROXTON_M_XHCI		0x0aa8
 #define PCI_DEVICE_ID_INTEL_BROXTON_B_XHCI		0x1aa8
+#define PCI_DEVICE_ID_INTEL_APL_XHCI			0x5aa8
 
 static const char hcd_name[] = "xhci_hcd";
 
@@ -145,6 +146,11 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 		 pdev->device == PCI_DEVICE_ID_INTEL_BROXTON_B_XHCI)) {
 		xhci->quirks |= XHCI_PME_STUCK_QUIRK;
 	}
+	if (pdev->vendor == PCI_VENDOR_ID_INTEL &&
+	    (pdev->device == PCI_DEVICE_ID_INTEL_CHERRYVIEW_XHCI ||
+	     pdev->device == PCI_DEVICE_ID_INTEL_APL_XHCI))
+		xhci->quirks |= XHCI_MISSING_CAS;
+
 	if (pdev->vendor == PCI_VENDOR_ID_ETRON &&
 			pdev->device == PCI_DEVICE_ID_ASROCK_P67) {
 		xhci->quirks |= XHCI_RESET_ON_RESUME;
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 0419137c4732..83bfb60d19c0 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -286,6 +286,8 @@ struct xhci_op_regs {
 #define XDEV_U2		(0x2 << 5)
 #define XDEV_U3		(0x3 << 5)
 #define XDEV_INACTIVE	(0x6 << 5)
+#define XDEV_POLLING	(0x7 << 5)
+#define XDEV_COMP_MODE  (0xa << 5)
 #define XDEV_RESUME	(0xf << 5)
 /* true: port has power (see HCC_PPC) */
 #define PORT_POWER	(1 << 9)
@@ -1555,6 +1557,7 @@ struct xhci_hcd {
 #define XHCI_SLOW_SUSPEND	(1 << 17)
 #define XHCI_SPURIOUS_WAKEUP	(1 << 18)
 #define XHCI_PME_STUCK_QUIRK	(1 << 20)
+#define XHCI_MISSING_CAS	(1 << 24)
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
 	/* There are two roothubs to keep track of bus suspend info for */
-- 
2.11.0