[PATCH 3.16 148/306] xhci: workaround for hosts missing CAS bit

Ben Hutchings
2017-02-15T23:48:54Z

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

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 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
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(+)

--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1222,6 +1222,35 @@ 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);
@@ -1256,6 +1285,14 @@ int xhci_bus_resume(struct usb_hcd *hcd)
int slot_id;

temp = readl(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
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -44,6 +44,7 @@
#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";

@@ -152,6 +153,11 @@ static void xhci_pci_quirks(struct devic
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;
--- 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)
@@ -1566,6 +1568,7 @@ struct xhci_hcd {
/* For controllers with a broken beyond repair streams implementation */
#define XHCI_BROKEN_STREAMS (1 << 19)
#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 */