From: Moiz Sonasath <[email protected]>

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 <[email protected]>
---
 drivers/usb/otg/twl6030-usb.c |   33 +++++++++++++++++++++++++++------
 1 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/otg/twl6030-usb.c b/drivers/usb/otg/twl6030-usb.c
index cfb5aa7..857de79 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 +374,35 @@ static int twl6030_enable_irq(struct otg_transceiver *x)
        return 0;
 }
 
+static void otg_set_vbus_work(struct work_struct *data)
+{
+       struct twl6030_usb *twl = container_of(data, struct twl6030_usb,
+                                                               set_vbus_work);
+
+       if (twl->vbus_enable)
+               twl6030_writeb(twl, TWL_MODULE_MAIN_CHARGE , 0x40,
+                                                       CHARGERUSB_CTRL1);
+       else
+               twl6030_writeb(twl, TWL_MODULE_MAIN_CHARGE , 0x00,
+                                                       CHARGERUSB_CTRL1);
+}
+
 static int twl6030_set_vbus(struct otg_transceiver *x, bool enabled)
 {
        struct twl6030_usb *twl = xceiv_to_twl(x);
 
+       if (enabled)
+               twl->vbus_enable = 1;
+       else
+               twl->vbus_enable = 0;
+
        /*
         * Start driving VBUS. Set OPA_MODE bit in CHARGERUSB_CTRL1
         * register. This enables boost mode.
         */
-       if (enabled)
-               twl6030_writeb(twl, TWL_MODULE_MAIN_CHARGE , 0x40,
-                                               CHARGERUSB_CTRL1);
-        else
-               twl6030_writeb(twl, TWL_MODULE_MAIN_CHARGE , 0x00,
-                                               CHARGERUSB_CTRL1);
+
+       schedule_work(&twl->set_vbus_work);
+
        return 0;
 }
 
@@ -444,6 +463,8 @@ 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,
-- 
1.6.0.4

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