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 <apelete@xxxxxxxxxxxx>
---
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
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