[PATCH 2/2] musb: sunxi: Force session end on babble errors in host-mode

[Hans de Goede]

The sunxi musb has a bug where sometimes it will generate a babble
error on device disconnect instead of a disconnect irq. When this
happens the musb-controller switches from host mode to device mode
(it clears MUSB_DEVCTL_SESSION and sets MUSB_DEVCTL_BDEVICE) and
gets stuck in this state.

Clearing this requires reporting Vbus low for 200 or more ms, but
on some devices Vbus is simply always high (host-only mode, no Vbus
control).

This commit calls sun4i_usb_phy_force_session_end() on babble errors
in host-mode, fixing the musb controller being stuck in this state
on systems without Vbus control; and also fixes the need to unplug
the usb-b -> usb-a cable to get out of this state on systems with
Vbus control.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/usb/musb/sunxi.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/usb/musb/sunxi.c b/drivers/usb/musb/sunxi.c
index 1408245..5079d90 100644
--- a/drivers/usb/musb/sunxi.c
+++ b/drivers/usb/musb/sunxi.c
@@ -192,8 +192,18 @@ static irqreturn_t sunxi_musb_interrupt(int irq, void *__hci)
 	 * normally babble never happens treat it as disconnect.
 	 */
 	if ((musb->int_usb & MUSB_INTR_BABBLE) && is_host_active(musb)) {
+		struct sunxi_glue *glue =
+				dev_get_drvdata(musb->controller->parent);
+
+		dev_warn(musb->controller->parent, "babble, treating as disconnect\n");
+
 		musb->int_usb &= ~MUSB_INTR_BABBLE;
 		musb->int_usb |= MUSB_INTR_DISCONNECT;
+		/*
+		 * Fix the musb controller sometimes getting stuck in
+		 * bdevice state after a babble error.
+		 */
+		sun4i_usb_phy_force_session_end(glue->phy);
 	}
 
 	if ((musb->int_usb & MUSB_INTR_RESET) && !is_host_active(musb)) {
-- 
2.9.3