usb: musb: fix idling for suspend after disconnect interrupt

When disconnected as USB B-device, suspend interrupt should come before
diconnect interrupt, because the DP/DM pins are shorter than the
VBUS/GND pins on the USB connectors. But we sometimes get a suspend
interrupt after disconnect interrupt. In that case we have devctl set to
99 with VBUS still valid and musb_pm_runtime_check_session() wrongly
thinks we have an active session. We have no other interrupts after
disconnect coming in this case at least with the omap2430 glue.

Let's fix the issue by checking the interrupt status again with
delayed work for the devctl 99 case. In the suspend after disconnect
case the devctl session bit has cleared by then and musb can idle.
For a typical USB B-device connect case we just continue with normal
interrupts.

Fixes: 467d5c9 ("usb: musb: Implement session bit based runtime PM for musb-core")

Cc: Merlijn Wajer <merlijn@wizzup.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200107152625.857-2-b-liu@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/musb/musb_core.c

@@ -1840,6 +1840,9 @@ ATTRIBUTE_GROUPS(musb);
 #define MUSB_QUIRK_B_INVALID_VBUS_91	(MUSB_DEVCTL_BDEVICE | \
 					 (2 << MUSB_DEVCTL_VBUS_SHIFT) | \
 					 MUSB_DEVCTL_SESSION)
+#define MUSB_QUIRK_B_DISCONNECT_99	(MUSB_DEVCTL_BDEVICE | \
+					 (3 << MUSB_DEVCTL_VBUS_SHIFT) | \
+					 MUSB_DEVCTL_SESSION)
 #define MUSB_QUIRK_A_DISCONNECT_19	((3 << MUSB_DEVCTL_VBUS_SHIFT) | \
 					 MUSB_DEVCTL_SESSION)
 
@@ -1862,6 +1865,11 @@ static void musb_pm_runtime_check_session(struct musb *musb)
 	s = MUSB_DEVCTL_FSDEV | MUSB_DEVCTL_LSDEV |
 		MUSB_DEVCTL_HR;
 	switch (devctl & ~s) {
+	case MUSB_QUIRK_B_DISCONNECT_99:
+		musb_dbg(musb, "Poll devctl in case of suspend after disconnect\n");
+		schedule_delayed_work(&musb->irq_work,
+				      msecs_to_jiffies(1000));
+		break;
 	case MUSB_QUIRK_B_INVALID_VBUS_91:
 		if (musb->quirk_retries && !musb->flush_irq_work) {
 			musb_dbg(musb,