JZ4740 USB Device Controller is not OTG compatible and does not have DEVCTL register in silicon.
During ethernet-over-usb transactions, on reset, musb driver tries to read from DEVCTL and consequently sets device as host (A-Device) instead of peripheral (B-Device), which makes it a composite device to the USB gadget driver. This induces a kernel panic during power down where the USB gadget driver does a null pointer dereference when trying to access the composite device configuration. On reset, do not rely on DEVCTL value for setting gadget peripheral mode: hardcode it instead to B-Device. Signed-off-by: Apelete Seketeli <[email protected]> --- drivers/usb/musb/musb_gadget.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c index 32fb057..b4bea7a 100644 --- a/drivers/usb/musb/musb_gadget.c +++ b/drivers/usb/musb/musb_gadget.c @@ -2119,6 +2119,14 @@ __acquires(musb->lock) /* Normal reset, as B-Device; * or else after HNP, as A-Device */ +#if defined(CONFIG_USB_MUSB_JZ4740) || defined(CONFIG_USB_MUSB_JZ4740_MODULE) + /* JZ4740 UDC Controller is not OTG compatible and does not + * have DEVCTL register in silicon: do not rely on devctl for + * setting peripheral mode. + */ + musb->xceiv->state = OTG_STATE_B_PERIPHERAL; + musb->g.is_a_peripheral = 0; +#else if (devctl & MUSB_DEVCTL_BDEVICE) { musb->xceiv->state = OTG_STATE_B_PERIPHERAL; musb->g.is_a_peripheral = 0; @@ -2126,6 +2134,7 @@ __acquires(musb->lock) musb->xceiv->state = OTG_STATE_A_PERIPHERAL; musb->g.is_a_peripheral = 1; } +#endif /* start with default limits on VBUS power draw */ (void) musb_gadget_vbus_draw(&musb->g, 8); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
