xhci: workaround for hosts missing CAS bit

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@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 13bb316..d89b72c 100644 (file)
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1036,6 +1036,35 @@ 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);
@@ -1070,6 +1099,14 @@ 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 fce6355..a6d4be0 100644 (file)
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -42,6 +42,7 @@
 #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";
 
@@ -141,6 +142,11 @@ 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 15f58d1..4453f2a 100644 (file)
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -280,6 +280,8 @@ struct xhci_op_regs {
 #define XDEV_U0                (0x0 << 5)
 #define XDEV_U2                (0x2 << 5)
 #define XDEV_U3                (0x3 << 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)
@@ -1499,6 +1501,7 @@ 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 */