[PATCH 1/2] USB: musb: fix late external abort on suspend

[Johan Hovold <johan@kernel.org>]

The musb delayed irq work was never flushed on suspend, something which
since 4.9 can lead to an external abort if the work is scheduled after
the grandparent's clock has been disabled:

PM: Suspending system (mem)
PM: suspend of devices complete after 125.224 msecs
PM: suspend devices took 0.132 seconds
PM: late suspend of devices complete after 7.423 msecs
PM: noirq suspend of devices complete after 7.083 msecs
suspend debug: Waiting for 5 second(s).
Unhandled fault: external abort on non-linefetch (0x1008) at 0xd0262c60
...
[<c054880c>] (musb_default_readb) from [<c0547b5c>] (musb_irq_work+0x48/0x220)
[<c0547b5c>] (musb_irq_work) from [<c014f8a4>] (process_one_work+0x1f4/0x758)
[<c014f8a4>] (process_one_work) from [<c014fe5c>] (worker_thread+0x54/0x514)
[<c014fe5c>] (worker_thread) from [<c015704c>] (kthread+0x128/0x158)
[<c015704c>] (kthread) from [<c0109330>] (ret_from_fork+0x14/0x24)

Commit 2bff3916fda9 ("usb: musb: Fix PM for hub disconnect") started
scheduling musb_irq_work with a delay of up to a second and with
retries thereby making this easy to trigger, for example, by suspending
shortly after a disconnect.

Note that the session flag is cleared and runtime-PM usage count
balanced after having cancelled the irq work instead of always
rescheduling on resume as the latter would have broken PM for host mode,
which always has the session bit set.

Fixes: 550a7375fe72 ("USB: Add MUSB and TUSB support")
Fixes: 467d5c980709 ("usb: musb: Implement session bit based runtime PM for musb-core")
Fixes: 2bff3916fda9 ("usb: musb: Fix PM for hub disconnect")
Cc: stable <stable@vger.kernel.org>     # 4.9
Cc: Felipe Balbi <felipe.balbi@linux.intel.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/musb/musb_core.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index b67692857daf..8645432337cb 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -2681,8 +2681,18 @@ static int musb_suspend(struct device *dev)
 
 	musb_platform_disable(musb);
 	musb_disable_interrupts(musb);
-	if (!(musb->io.quirks & MUSB_PRESERVE_SESSION))
+
+	cancel_delayed_work_sync(&musb->irq_work);
+
+	if (!(musb->io.quirks & MUSB_PRESERVE_SESSION)) {
 		musb_writeb(musb->mregs, MUSB_DEVCTL, 0);
+
+		if (musb->session) {
+			musb->session = false;
+			pm_runtime_put_noidle(musb->controller);
+		}
+	}
+
 	WARN_ON(!list_empty(&musb->pending_list));
 
 	spin_lock_irqsave(&musb->lock, flags);
-- 
2.14.1