USB: OTG: Use work_queue in set_vbus for TWL6030 transciever

With this commit: cccad6d4b103e53fb3d1fc1467f654ecb572d047
usb: otg: notifier: switch to atomic notifier

Following dumps are observed on attach/detach for MUSB HOST
mode and on a detach for MUSB Device mode.

BUG: sleeping function called from invalid context at kernel/mutex.c:85
where, the source is:
twl6030_usb_irq
->atomic_notifier_call_chain
 ->musb_otg_notifications
  ->twl6030_set_vbus
   ->twl_i2c_write_u8
    ->mutex_lock

This patch moves the i2c writes in set_vbus function to a
work-queue thereby avoiding I2C writes in atomic context.

Tested HOST and Device mode functionality on OMAP4460

Signed-off-by: Moiz Sonasath <m-sonasath@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 24 insertions, 6 deletions

diff --git a/drivers/usb/otg/twl6030-usb.c b/drivers/usb/otg/twl6030-usb.c
index cfb5aa72b196..b4d2c0972b3d 100644
--- a/drivers/usb/otg/twl6030-usb.c
+++ b/drivers/usb/otg/twl6030-usb.c
@@ -95,11 +95,15 @@ struct twl6030_usb {
 
         struct regulator                *usb3v3;
 
+        /* used to set vbus, in atomic path */
+        struct work_struct      set_vbus_work;
+
         int                     irq1;
         int                     irq2;
         u8                      linkstat;
         u8                      asleep;
         bool                    irq_enabled;
+        bool                    vbus_enable;
         unsigned long           features;
 };
 
@@ -370,20 +374,31 @@ static int twl6030_enable_irq(struct otg_transceiver *x)
         return 0;
 }
 
-static int twl6030_set_vbus(struct otg_transceiver *x, bool enabled)
+static void otg_set_vbus_work(struct work_struct *data)
 {
-        struct twl6030_usb *twl = xceiv_to_twl(x);
+        struct twl6030_usb *twl = container_of(data, struct twl6030_usb,
+                                                                set_vbus_work);
 
         /*
          * Start driving VBUS. Set OPA_MODE bit in CHARGERUSB_CTRL1
          * register. This enables boost mode.
          */
-        if (enabled)
+
+        if (twl->vbus_enable)
                 twl6030_writeb(twl, TWL_MODULE_MAIN_CHARGE , 0x40,
-                                                CHARGERUSB_CTRL1);
-         else
+                                                        CHARGERUSB_CTRL1);
+        else
                 twl6030_writeb(twl, TWL_MODULE_MAIN_CHARGE , 0x00,
-                                                CHARGERUSB_CTRL1);
+                                                        CHARGERUSB_CTRL1);
+}
+
+static int twl6030_set_vbus(struct otg_transceiver *x, bool enabled)
+{
+        struct twl6030_usb *twl = xceiv_to_twl(x);
+
+        twl->vbus_enable = enabled;
+        schedule_work(&twl->set_vbus_work);
+
         return 0;
 }
 
@@ -444,6 +459,8 @@ static int __devinit twl6030_usb_probe(struct platform_device *pdev)
 
         ATOMIC_INIT_NOTIFIER_HEAD(&twl->otg.notifier);
 
+        INIT_WORK(&twl->set_vbus_work, otg_set_vbus_work);
+
         twl->irq_enabled = true;
         status = request_threaded_irq(twl->irq1, NULL, twl6030_usbotg_irq,
                         IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
@@ -494,6 +511,7 @@ static int __exit twl6030_usb_remove(struct platform_device *pdev)
         regulator_put(twl->usb3v3);
         pdata->phy_exit(twl->dev);
         device_remove_file(twl->dev, &dev_attr_vbus);
+        cancel_work_sync(&twl->set_vbus_work);
         kfree(twl);
 
         return 0;