mdm6600: Fix irq storm on disconnect

When the modem is powered off, the driver might receive interupts
before usb has detected that the modem is disconnected. Disable
the interrupt in the irq handler before resuming the modem.

Change-Id: I866c64dea0da4cff6aa7947224255378790b160c
Signed-off-by: Benoit Goby <benoit@android.com>

diff --git a/drivers/usb/serial/mdm6600.c b/drivers/usb/serial/mdm6600.c
index fe2d2530d62d24fd9fcd5333d8b21d9e701dc480..ececf76ce6e4a8749ed1addba0d2b6a5b2b450b6 100644 (file)
--- a/drivers/usb/serial/mdm6600.c
+++ b/drivers/usb/serial/mdm6600.c
@@ -102,6 +102,9 @@ struct mdm6600_port {
 };
 
 static int mdm6600_wake_irq;
+static bool mdm6600_wake_irq_enabled;
+static DEFINE_SPINLOCK(mdm6600_wake_irq_lock);
+
 /*
  * Count the number of attached ports. Don't use port->number as it may
  * changed if other ttyUSB have been registered before.
@@ -141,6 +144,13 @@ static irqreturn_t mdm6600_irq_handler(int irq, void *ptr)
 {
        struct mdm6600_port *modem = ptr;
 
+       spin_lock(&mdm6600_wake_irq_lock);
+       if (mdm6600_wake_irq_enabled) {
+               disable_irq_nosync(irq);
+               mdm6600_wake_irq_enabled = false;
+       }
+       spin_unlock(&mdm6600_wake_irq_lock);
+
        wake_lock_timeout(&modem->readlock, MODEM_WAKELOCK_TIME);
        queue_work(system_nrt_wq, &modem->wake_work);
 
@@ -495,6 +505,13 @@ static int mdm6600_write(struct tty_struct *tty, struct usb_serial_port *port,
        }
        spin_unlock_irqrestore(&modem->write.pending_lock, flags);
 
+       spin_lock_irqsave(&mdm6600_wake_irq_lock, flags);
+       if (mdm6600_wake_irq_enabled) {
+               disable_irq_nosync(mdm6600_wake_irq);
+               mdm6600_wake_irq_enabled = false;
+       }
+       spin_unlock_irqrestore(&mdm6600_wake_irq_lock, flags);
+
        spin_lock_irqsave(&modem->susp_lock, flags);
        if (modem->susp_count) {
                usb_anchor_urb(u, &modem->write.delayed);
@@ -823,10 +840,16 @@ static int mdm6600_suspend(struct usb_interface *intf, pm_message_t message)
 
        dbg("%s: event=%d", __func__, message.event);
 
-       spin_lock_irq(&modem->susp_lock);
+       if (modem->number == MODEM_INTERFACE_NUM) {
+               spin_lock_irq(&mdm6600_wake_irq_lock);
+               if (!mdm6600_wake_irq_enabled) {
+                       enable_irq(mdm6600_wake_irq);
+                       mdm6600_wake_irq_enabled = true;
+               }
+               spin_unlock_irq(&mdm6600_wake_irq_lock);
+       }
 
-       if (modem->number == MODEM_INTERFACE_NUM)
-               enable_irq(mdm6600_wake_irq);
+       spin_lock_irq(&modem->susp_lock);
 
        if (!modem->susp_count++ && modem->opened) {
                spin_unlock_irq(&modem->susp_lock);
@@ -851,9 +874,6 @@ static int mdm6600_resume(struct usb_interface *intf)
 
        spin_lock_irq(&modem->susp_lock);
 
-       if (modem->number == MODEM_INTERFACE_NUM)
-               disable_irq(mdm6600_wake_irq);
-
        if (!--modem->susp_count && modem->opened) {
                dbg("%s: submit urbs", __func__);
                spin_unlock_irq(&modem->susp_lock);