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Subject[PATCH v2 5/5] xhci: add a quirk for device disconnection errata for Synopsis Designware USB3 core
Date
This issue is defined by a three-way race at disconnect, between
1) Class driver interrupt endpoint resheduling attempts if the ISR gave an ep
error event due to device detach (it would try 3 times)
2) Disconnect interrupt on PORTSC_CSC, which is cleared by hub thread
asynchronously
3) The hardware IP was configured in silicon with
- DWC_USB3_SUSPEND_ON_DISCONNECT_EN=1
- Synopsys IP version is < 3.00a
The IP will auto-suspend itself on device detach with some phy-specific interval
after CSC is cleared by 2)

If 2) and 3) complete before 1), the interrupts it expects will not be generated
by the autosuspended IP, leading to a deadlock. Even later disconnection
procedure would detect that corresponding urb is still in-progress and issue a
ep stop command, auto-suspended IP still won't respond to that command.

this defect would result in this when device detached:
-------------------------------------------------------
[ 99.603544] usb 4-1: USB disconnect, device number 2
[ 104.615254] xhci-hcd xhci-hcd.0.auto: xHCI host not responding to stop endpoint command.
[ 104.623362] xhci-hcd xhci-hcd.0.auto: Assuming host is dying, halting host.
[ 104.653261] xhci-hcd xhci-hcd.0.auto: Host not halted after 16000 microseconds.
[ 104.660584] xhci-hcd xhci-hcd.0.auto: Non-responsive xHCI host is not halting.
[ 104.667817] xhci-hcd xhci-hcd.0.auto: Completing active URBs anyway.
[ 104.674198] xhci-hcd xhci-hcd.0.auto: HC died; cleaning up
------------------------------------------------------
As a result, when device detached, we desired to postpone "PORTCSC clear" behind
"disable slot". it's found that all executed ep command related to disconnetion,
are executed before "disable slot".

Signed-off-by: Sneeker Yeh <Sneeker.Yeh@tw.fujitsu.com>
---
drivers/usb/host/xhci-hub.c | 4 ++++
drivers/usb/host/xhci.c | 29 +++++++++++++++++++++++++++++
drivers/usb/host/xhci.h | 24 ++++++++++++++++++++++++
3 files changed, 57 insertions(+)

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index a7865c4..3b8f7fc 100644
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -368,6 +368,10 @@ static void xhci_clear_port_change_bit(struct xhci_hcd *xhci, u16 wValue,
port_change_bit = "warm(BH) reset";
break;
case USB_PORT_FEAT_C_CONNECTION:
+ if ((xhci->quirks & XHCI_DISCONNECT_QUIRK) &&
+ !(readl(addr) & PORT_CONNECT))
+ return;
+
status = PORT_CSC;
port_change_bit = "connect";
break;
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index c50d8d2..aa8e02a 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3584,6 +3584,33 @@ command_cleanup:
return ret;
}

+static void xhci_try_to_clear_csc(struct usb_hcd *hcd, int dev_port_num)
+{
+ int max_ports;
+ struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+ __le32 __iomem **port_array;
+ u32 status;
+
+ /* print debug info */
+ if (hcd->speed == HCD_USB3) {
+ max_ports = xhci->num_usb3_ports;
+ port_array = xhci->usb3_ports;
+ } else {
+ max_ports = xhci->num_usb2_ports;
+ port_array = xhci->usb2_ports;
+ }
+
+ if (dev_port_num > max_ports) {
+ xhci_err(xhci, "%s() port number invalid", __func__);
+ return;
+ }
+ status = readl(port_array[dev_port_num - 1]);
+
+ /* write 1 to clear */
+ if (!(status & PORT_CONNECT) && (status & PORT_CSC))
+ writel(status & PORT_CSC, port_array[0]);
+}
+
/*
* At this point, the struct usb_device is about to go away, the device has
* disconnected, and all traffic has been stopped and the endpoints have been
@@ -3649,6 +3676,8 @@ void xhci_free_dev(struct usb_hcd *hcd, struct usb_device *udev)
xhci_ring_cmd_db(xhci);
spin_unlock_irqrestore(&xhci->lock, flags);

+ if (xhci->quirks & XHCI_DISCONNECT_QUIRK)
+ xhci_try_to_clear_csc(hcd, udev->portnum);
/*
* Event command completion handler will free any data structures
* associated with the slot. XXX Can free sleep?
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index cc7c5bb..65a65cc 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1560,6 +1560,30 @@ struct xhci_hcd {
#define XHCI_SPURIOUS_WAKEUP (1 << 18)
/* For controllers with a broken beyond repair streams implementation */
#define XHCI_BROKEN_STREAMS (1 << 19)
+/*
+ * This issue is defined by a three-way race at disconnect in Synopsis USB3 IP,
+ * between
+ * 1) Class driver interrupt endpoint resheduling attempts if the ISR gave an ep
+ * error event due to device detach (it would try 3 times)
+ * 2) Disconnect interrupt on PORTSC_CSC, which is cleared by hub thread
+ * asynchronously
+ * 3) The hardware IP was configured in silicon with
+ * - DWC_USB3_SUSPEND_ON_DISCONNECT_EN=1
+ * - Synopsys IP version is < 3.00a
+ * The IP will auto-suspend itself on device detach with some phy-specific
+ * interval after CSC is cleared by 2)
+ *
+ * If 2) and 3) complete before 1), the interrupts it expects will not be
+ * generated by the autosuspended IP, leading to a deadlock. Even later
+ * disconnection procedure would detect that corresponding urb is still
+ * in-progress and issue a ep stop command, auto-suspended IP still won't
+ * respond to that command.
+ *
+ * As a result, when device detached, it's needed to postpone "PORTCSC clear"
+ * behind "disable slot". it's found that all executed ep command related to
+ * disconnetion, are executed before "disable slot".
+ */
+#define XHCI_DISCONNECT_QUIRK (1 << 20)
unsigned int num_active_eps;
unsigned int limit_active_eps;
/* There are two roothubs to keep track of bus suspend info for */
--
1.7.9.5


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