USB: add new routine for checking port-resume type

This patch (as1070) creates a new subroutine to check whether a device
can be resumed.  This code is needed even when CONFIG_USB_SUSPEND
isn't set, because devices do suspend themselves when the root hub
(and hence the entire bus) is suspended, and power sessions can get
lost during a system sleep even without individual port suspends.

The patch also fixes a loose end in USB-Persist reset-resume handling.
When a low- or full-speed device is attached to an EHCI's companion
controller, the port handoff during resume will cause the companion
port's connect-status-change feature to be set.  If that flag isn't
cleared, the port-reset code will think it indicates that the device
has been unplugged and the reset-resume will fail.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 63 insertions, 26 deletions

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 2a5c2833de38..d14da2123eb5 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1821,6 +1821,45 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
 
 #ifdef  CONFIG_PM
 
+#define MASK_BITS       (USB_PORT_STAT_POWER | USB_PORT_STAT_CONNECTION | \
+                                USB_PORT_STAT_SUSPEND)
+#define WANT_BITS       (USB_PORT_STAT_POWER | USB_PORT_STAT_CONNECTION)
+
+/* Determine whether the device on a port is ready for a normal resume,
+ * is ready for a reset-resume, or should be disconnected.
+ */
+static int check_port_resume_type(struct usb_device *udev,
+                struct usb_hub *hub, int port1,
+                int status, unsigned portchange, unsigned portstatus)
+{
+        /* Is the device still present? */
+        if (status || (portstatus & MASK_BITS) != WANT_BITS) {
+                if (status >= 0)
+                        status = -ENODEV;
+        }
+
+        /* Can't do a normal resume if the port isn't enabled */
+        else if (!(portstatus & USB_PORT_STAT_ENABLE) && !udev->reset_resume)
+                status = -ENODEV;
+
+        if (status) {
+                dev_dbg(hub->intfdev,
+                                "port %d status %04x.%04x after resume, %d\n",
+                                port1, portchange, portstatus, status);
+        } else if (udev->reset_resume) {
+
+                /* Late port handoff can set status-change bits */
+                if (portchange & USB_PORT_STAT_C_CONNECTION)
+                        clear_port_feature(hub->hdev, port1,
+                                        USB_PORT_FEAT_C_CONNECTION);
+                if (portchange & USB_PORT_STAT_C_ENABLE)
+                        clear_port_feature(hub->hdev, port1,
+                                        USB_PORT_FEAT_C_ENABLE);
+        }
+
+        return status;
+}
+
 #ifdef  CONFIG_USB_SUSPEND
 
 /*
@@ -2025,7 +2064,6 @@ int usb_port_resume(struct usb_device *udev)
         int             port1 = udev->portnum;
         int             status;
         u16             portchange, portstatus;
-        unsigned        mask_flags, want_flags;
 
         /* Skip the initial Clear-Suspend step for a remote wakeup */
         status = hub_port_status(hub, port1, &portstatus, &portchange);
@@ -2054,35 +2092,23 @@ int usb_port_resume(struct usb_device *udev)
                  */
                 status = hub_port_status(hub, port1, &portstatus, &portchange);
 
- SuspendCleared:
-                if (udev->reset_resume)
-                        want_flags = USB_PORT_STAT_POWER
-                                        | USB_PORT_STAT_CONNECTION;
-                else
-                        want_flags = USB_PORT_STAT_POWER
-                                        | USB_PORT_STAT_CONNECTION
-                                        | USB_PORT_STAT_ENABLE;
-                mask_flags = want_flags | USB_PORT_STAT_SUSPEND;
+                /* TRSMRCY = 10 msec */
+                msleep(10);
+        }
 
-                if (status < 0 || (portstatus & mask_flags) != want_flags) {
-                        dev_dbg(hub->intfdev,
-                                "port %d status %04x.%04x after resume, %d\n",
-                                port1, portchange, portstatus, status);
-                        if (status >= 0)
-                                status = -ENODEV;
-                } else {
-                        if (portchange & USB_PORT_STAT_C_SUSPEND)
-                                clear_port_feature(hub->hdev, port1,
-                                                USB_PORT_FEAT_C_SUSPEND);
-                        /* TRSMRCY = 10 msec */
-                        msleep(10);
-                }
+ SuspendCleared:
+        if (status == 0) {
+                if (portchange & USB_PORT_STAT_C_SUSPEND)
+                        clear_port_feature(hub->hdev, port1,
+                                        USB_PORT_FEAT_C_SUSPEND);
         }
 
         clear_bit(port1, hub->busy_bits);
         if (!hub->hdev->parent && !hub->busy_bits[0])
                 usb_enable_root_hub_irq(hub->hdev->bus);
 
+        status = check_port_resume_type(udev,
+                        hub, port1, status, portchange, portstatus);
         if (status == 0)
                 status = finish_port_resume(udev);
         if (status < 0) {
@@ -2115,12 +2141,23 @@ int usb_port_suspend(struct usb_device *udev)
         return 0;
 }
 
+/* However we may need to do a reset-resume */
+
 int usb_port_resume(struct usb_device *udev)
 {
-        int status = 0;
+        struct usb_hub  *hub = hdev_to_hub(udev->parent);
+        int             port1 = udev->portnum;
+        int             status;
+        u16             portchange, portstatus;
 
-        /* However we may need to do a reset-resume */
-        if (udev->reset_resume) {
+        status = hub_port_status(hub, port1, &portstatus, &portchange);
+        status = check_port_resume_type(udev,
+                        hub, port1, status, portchange, portstatus);
+
+        if (status) {
+                dev_dbg(&udev->dev, "can't resume, status %d\n", status);
+                hub_port_logical_disconnect(hub, port1);
+        } else if (udev->reset_resume) {
                 dev_dbg(&udev->dev, "reset-resume\n");
                 status = usb_reset_device(udev);
         }