diff options
| author | Alan Stern | 2008-04-28 11:06:28 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2008-07-21 15:15:47 -0700 |
| commit | 24618b0cd42f936cda461bdf6144670a5c925178 (patch) | |
| tree | dfcc0d831eb24f7466bbb3ebb2a69b3d93622120 /drivers | |
| parent | b01b03f3ad82b4293f6ca4da9b2692b6a377c609 (diff) | |
USB: debounce before unregistering
This patch (as1080) makes a significant change to the way khubd
handles port connect-change and enable-change events. Both types of
event are now debounced, and the debouncing is carried out _before_ an
existing usb_device is unregistered, instead of afterward.
This means that drivers will have to deal with longer runs of errors
when a device is unplugged, but they are supposed to be prepared for
that in any case.
The advantage is that when an enable-change occurs (caused for example
by electromagnetic interference), the debouncing period will provide
time for the cause of the problem to die away. A simple port reset
(added in a forthcoming patch) will then allow us to recover from the
fault.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/core/hub.c | 31 |
1 files changed, 19 insertions, 12 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index d14da2123eb5..d741b9457427 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -2673,9 +2673,10 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, struct usb_device *hdev = hub->hdev; struct device *hub_dev = hub->intfdev; struct usb_hcd *hcd = bus_to_hcd(hdev->bus); - u16 wHubCharacteristics = le16_to_cpu(hub->descriptor->wHubCharacteristics); + unsigned wHubCharacteristics = + le16_to_cpu(hub->descriptor->wHubCharacteristics); int status, i; - + dev_dbg (hub_dev, "port %d, status %04x, change %04x, %s\n", port1, portstatus, portchange, portspeed (portstatus)); @@ -2684,30 +2685,36 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, set_port_led(hub, port1, HUB_LED_AUTO); hub->indicator[port1-1] = INDICATOR_AUTO; } - - /* Disconnect any existing devices under this port */ - if (hdev->children[port1-1]) - usb_disconnect(&hdev->children[port1-1]); - clear_bit(port1, hub->change_bits); #ifdef CONFIG_USB_OTG /* during HNP, don't repeat the debounce */ if (hdev->bus->is_b_host) - portchange &= ~USB_PORT_STAT_C_CONNECTION; + portchange &= ~(USB_PORT_STAT_C_CONNECTION | + USB_PORT_STAT_C_ENABLE); #endif - if (portchange & USB_PORT_STAT_C_CONNECTION) { + /* Try to use the debounce delay for protection against + * port-enable changes caused, for example, by EMI. + */ + if (portchange & (USB_PORT_STAT_C_CONNECTION | + USB_PORT_STAT_C_ENABLE)) { status = hub_port_debounce(hub, port1); if (status < 0) { if (printk_ratelimit()) dev_err (hub_dev, "connect-debounce failed, " "port %d disabled\n", port1); - goto done; + portstatus &= ~USB_PORT_STAT_CONNECTION; + } else { + portstatus = status; } - portstatus = status; } - /* Return now if nothing is connected */ + /* Disconnect any existing devices under this port */ + if (hdev->children[port1-1]) + usb_disconnect(&hdev->children[port1-1]); + clear_bit(port1, hub->change_bits); + + /* Return now if debouncing failed or nothing is connected */ if (!(portstatus & USB_PORT_STAT_CONNECTION)) { /* maybe switch power back on (e.g. root hub was reset) */ |