USB: add USB-Persist facility
This patch (as886) adds the controversial USB-persist facility, allowing USB devices to persist across a power loss during system suspend. The facility is controlled by a new Kconfig option (with appropriate warnings about the potential dangers); when the option is off the behavior will remain the same as it is now. But when the option is on, people will be able to use suspend-to-disk and keep their USB filesystems intact -- something particularly valuable for small machines where the root filesystem is on a USB device! Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Stern
committed by
Greg Kroah-Hartman
Greg Kroah-Hartman
parent
ce7cd137fc
commit
0458d5b4c9
@@ -553,45 +553,121 @@ static int hub_hub_status(struct usb_hub *hub,
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static int hub_port_disable(struct usb_hub *hub, int port1, int set_state)
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{
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struct usb_device *hdev = hub->hdev;
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int ret;
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int ret = 0;
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if (hdev->children[port1-1] && set_state) {
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if (hdev->children[port1-1] && set_state)
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usb_set_device_state(hdev->children[port1-1],
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USB_STATE_NOTATTACHED);
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}
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ret = clear_port_feature(hdev, port1, USB_PORT_FEAT_ENABLE);
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if (!hub->error)
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ret = clear_port_feature(hdev, port1, USB_PORT_FEAT_ENABLE);
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if (ret)
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dev_err(hub->intfdev, "cannot disable port %d (err = %d)\n",
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port1, ret);
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port1, ret);
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return ret;
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}
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/*
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* Disable a port and mark a logical connnect-change event, so that some
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* time later khubd will disconnect() any existing usb_device on the port
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* and will re-enumerate if there actually is a device attached.
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*/
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static void hub_port_logical_disconnect(struct usb_hub *hub, int port1)
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{
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dev_dbg(hub->intfdev, "logical disconnect on port %d\n", port1);
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hub_port_disable(hub, port1, 1);
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/* FIXME let caller ask to power down the port:
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* - some devices won't enumerate without a VBUS power cycle
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* - SRP saves power that way
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* - ... new call, TBD ...
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* That's easy if this hub can switch power per-port, and
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* khubd reactivates the port later (timer, SRP, etc).
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* Powerdown must be optional, because of reset/DFU.
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*/
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set_bit(port1, hub->change_bits);
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kick_khubd(hub);
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}
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static void disconnect_all_children(struct usb_hub *hub, int logical)
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{
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struct usb_device *hdev = hub->hdev;
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int port1;
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for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
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if (hdev->children[port1-1]) {
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if (logical)
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hub_port_logical_disconnect(hub, port1);
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else
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usb_disconnect(&hdev->children[port1-1]);
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}
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}
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}
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#ifdef CONFIG_USB_PERSIST
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#define USB_PERSIST 1
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/* For "persistent-device" resets we must mark the child devices for reset
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* and turn off a possible connect-change status (so khubd won't disconnect
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* them later).
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*/
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static void mark_children_for_reset_resume(struct usb_hub *hub)
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{
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struct usb_device *hdev = hub->hdev;
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int port1;
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for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
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struct usb_device *child = hdev->children[port1-1];
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if (child) {
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child->reset_resume = 1;
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clear_port_feature(hdev, port1,
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USB_PORT_FEAT_C_CONNECTION);
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}
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}
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}
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#else
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#define USB_PERSIST 0
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static inline void mark_children_for_reset_resume(struct usb_hub *hub)
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{ }
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#endif /* CONFIG_USB_PERSIST */
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/* caller has locked the hub device */
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static void hub_pre_reset(struct usb_interface *intf)
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{
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struct usb_hub *hub = usb_get_intfdata(intf);
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struct usb_device *hdev = hub->hdev;
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int port1;
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for (port1 = 1; port1 <= hdev->maxchild; ++port1) {
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if (hdev->children[port1 - 1]) {
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usb_disconnect(&hdev->children[port1 - 1]);
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if (hub->error == 0)
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hub_port_disable(hub, port1, 0);
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}
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}
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/* This routine doesn't run as part of a reset-resume, so it's safe
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* to disconnect all the drivers below the hub.
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*/
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disconnect_all_children(hub, 0);
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hub_quiesce(hub);
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}
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/* caller has locked the hub device */
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static void hub_post_reset(struct usb_interface *intf)
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static void hub_post_reset(struct usb_interface *intf, int reset_resume)
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{
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struct usb_hub *hub = usb_get_intfdata(intf);
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hub_activate(hub);
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hub_power_on(hub);
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if (reset_resume) {
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if (USB_PERSIST)
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mark_children_for_reset_resume(hub);
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else {
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/* Reset-resume doesn't call pre_reset, so we have to
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* disconnect the children here. But we may not lock
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* the child devices, so we have to do a "logical"
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* disconnect.
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*/
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disconnect_all_children(hub, 1);
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}
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}
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hub_activate(hub);
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}
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@@ -1053,33 +1129,64 @@ void usb_set_device_state(struct usb_device *udev,
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#ifdef CONFIG_PM
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/**
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* usb_reset_suspended_device - reset a suspended device instead of resuming it
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* @udev: device to be reset instead of resumed
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*
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* If a host controller doesn't maintain VBUS suspend current during a
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* system sleep or is reset when the system wakes up, all the USB
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* power sessions below it will be broken. This is especially troublesome
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* for mass-storage devices containing mounted filesystems, since the
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* device will appear to have disconnected and all the memory mappings
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* to it will be lost.
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*
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* As an alternative, this routine attempts to recover power sessions for
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* devices that are still present by resetting them instead of resuming
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* them. If all goes well, the devices will appear to persist across the
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* the interruption of the power sessions.
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*
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* This facility is inherently dangerous. Although usb_reset_device()
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* makes every effort to insure that the same device is present after the
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* reset as before, it cannot provide a 100% guarantee. Furthermore it's
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* quite possible for a device to remain unaltered but its media to be
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* changed. If the user replaces a flash memory card while the system is
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* asleep, he will have only himself to blame when the filesystem on the
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* new card is corrupted and the system crashes.
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*/
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int usb_reset_suspended_device(struct usb_device *udev)
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{
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int rc = 0;
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dev_dbg(&udev->dev, "usb %sresume\n", "reset-");
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/* After we're done the device won't be suspended any more.
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* In addition, the reset won't work if udev->state is SUSPENDED.
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*/
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usb_set_device_state(udev, udev->actconfig
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? USB_STATE_CONFIGURED
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: USB_STATE_ADDRESS);
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/* Root hubs don't need to be (and can't be) reset */
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if (udev->parent)
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rc = usb_reset_device(udev);
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return rc;
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}
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/**
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* usb_root_hub_lost_power - called by HCD if the root hub lost Vbus power
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* @rhdev: struct usb_device for the root hub
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*
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* The USB host controller driver calls this function when its root hub
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* is resumed and Vbus power has been interrupted or the controller
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* has been reset. The routine marks all the children of the root hub
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* as NOTATTACHED and marks logical connect-change events on their ports.
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* has been reset. The routine marks @rhdev as having lost power. When
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* the hub driver is resumed it will take notice; if CONFIG_USB_PERSIST
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* is enabled then it will carry out power-session recovery, otherwise
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* it will disconnect all the child devices.
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*/
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void usb_root_hub_lost_power(struct usb_device *rhdev)
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{
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struct usb_hub *hub;
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int port1;
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unsigned long flags;
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dev_warn(&rhdev->dev, "root hub lost power or was reset\n");
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spin_lock_irqsave(&device_state_lock, flags);
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hub = hdev_to_hub(rhdev);
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for (port1 = 1; port1 <= rhdev->maxchild; ++port1) {
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if (rhdev->children[port1 - 1]) {
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recursively_mark_NOTATTACHED(
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rhdev->children[port1 - 1]);
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set_bit(port1, hub->change_bits);
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}
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}
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spin_unlock_irqrestore(&device_state_lock, flags);
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rhdev->reset_resume = 1;
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}
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EXPORT_SYMBOL_GPL(usb_root_hub_lost_power);
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@@ -1513,29 +1620,6 @@ static int hub_port_reset(struct usb_hub *hub, int port1,
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return status;
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}
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/*
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* Disable a port and mark a logical connnect-change event, so that some
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* time later khubd will disconnect() any existing usb_device on the port
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* and will re-enumerate if there actually is a device attached.
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*/
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static void hub_port_logical_disconnect(struct usb_hub *hub, int port1)
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{
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dev_dbg(hub->intfdev, "logical disconnect on port %d\n", port1);
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hub_port_disable(hub, port1, 1);
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/* FIXME let caller ask to power down the port:
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* - some devices won't enumerate without a VBUS power cycle
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* - SRP saves power that way
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* - ... new call, TBD ...
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* That's easy if this hub can switch power per-port, and
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* khubd reactivates the port later (timer, SRP, etc).
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* Powerdown must be optional, because of reset/DFU.
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*/
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set_bit(port1, hub->change_bits);
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kick_khubd(hub);
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}
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#ifdef CONFIG_PM
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#ifdef CONFIG_USB_SUSPEND
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@@ -3018,7 +3102,7 @@ int usb_reset_composite_device(struct usb_device *udev,
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cintf->dev.driver) {
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drv = to_usb_driver(cintf->dev.driver);
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if (drv->post_reset)
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(drv->post_reset)(cintf);
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(drv->post_reset)(cintf, 0);
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}
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if (cintf != iface)
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up(&cintf->dev.sem);
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