musb VBUS workaround

For some reason VBUS never falls after cable is disconnected
on pandora. The voltage can be even measured with a multimeter.
This is not the case on a friend's beagle. So this hack was written
to work around this.

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 920f04e..a03c5b2 100644 (file)
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -654,6 +654,15 @@ static irqreturn_t musb_stage0_irq(struct musb *musb, u8 int_usb,
                        musb->is_active = 0;
                        break;
                }
+
+               switch (musb->xceiv->state) {
+               case OTG_STATE_B_IDLE:
+               case OTG_STATE_B_PERIPHERAL:
+                       cancel_delayed_work(&musb->vbus_workaround_work);
+                       schedule_delayed_work(&musb->vbus_workaround_work, HZ / 2);
+               default:
+                       break;
+               }
        }
 
        if (int_usb & MUSB_INTR_CONNECT) {
@@ -993,6 +1002,9 @@ static void musb_shutdown(struct platform_device *pdev)
        musb_platform_exit(musb);
 
        pm_runtime_put(musb->controller);
+
+       cancel_delayed_work(&musb->vbus_workaround_work);
+
        /* FIXME power down */
 }
 
@@ -1770,6 +1782,41 @@ static void musb_irq_work(struct work_struct *data)
        }
 }
 
+#include <linux/usb/ulpi.h>
+
+static void musb_vbus_workaround_work(struct work_struct *work)
+{
+       struct musb *musb = container_of(work, struct musb, vbus_workaround_work.work);
+       u8 devctl;
+       int ret;
+
+       if (musb_ulpi_access.write == NULL)
+               return;
+
+       devctl = musb_readb(musb->mregs, MUSB_DEVCTL);
+
+       /*
+        * I don't really know why but VBUS sometimes gets stuck and
+        * causes session to never end. It would look like some pullup
+        * is enabled when it shouldn't be on certain PHY states.
+        * Turning on pulldowns magically drains VBUS to zero and allows
+        * session to end, so let's do that here.
+        *
+        * XXX: probably better check VBUS on TWL?
+        * beagle sometimes has session bit set but no VBUS on twl?
+        */
+       if ((musb->xceiv->state == OTG_STATE_B_PERIPHERAL ||
+            musb->xceiv->state == OTG_STATE_B_IDLE) &&
+           (devctl & MUSB_DEVCTL_VBUS) != (3 << MUSB_DEVCTL_VBUS_SHIFT) &&
+           (devctl & MUSB_DEVCTL_VBUS) != (0 << MUSB_DEVCTL_VBUS_SHIFT)) {
+               dev_dbg(musb->controller, "VBUS workaround..\n");
+               ret = musb_ulpi_access.write(musb->xceiv, ULPI_SET(ULPI_OTG_CTRL),
+                       ULPI_OTG_CTRL_DM_PULLDOWN | ULPI_OTG_CTRL_DP_PULLDOWN);
+               //if (ret)
+               //      dev_err(musb->controller, "VBUS workaround error\n");
+       }
+}
+
 /* --------------------------------------------------------------------------
  * Init support
  */
@@ -1941,6 +1988,8 @@ musb_init_controller(struct device *dev, int nIrq, void __iomem *ctrl)
        /* Init IRQ workqueue before request_irq */
        INIT_WORK(&musb->irq_work, musb_irq_work);
 
+       INIT_DELAYED_WORK(&musb->vbus_workaround_work, musb_vbus_workaround_work);
+
        /* attach to the IRQ */
        if (request_irq(nIrq, musb->isr, 0, dev_name(dev), musb)) {
                dev_err(dev, "request_irq %d failed!\n", nIrq);

diff --git a/drivers/usb/musb/musb_core.h b/drivers/usb/musb/musb_core.h
index b3c065a..01ec1a5 100644 (file)
--- a/drivers/usb/musb/musb_core.h
+++ b/drivers/usb/musb/musb_core.h
@@ -454,6 +454,7 @@ struct musb {
 #ifdef MUSB_CONFIG_PROC_FS
        struct proc_dir_entry *proc_entry;
 #endif
+       struct delayed_work     vbus_workaround_work;
 };
 
 static inline struct musb *gadget_to_musb(struct usb_gadget *g)