The current session-bit quirk implementation does not prevent the retry
counter from underflowing, something which could break runtime PM and
keep the device active for a very long time (about 2^32 seconds) after a
disconnect.

This notably breaks the B-device timeout case, but could potentially
cause problems also when the controller is operating as an A-device.

Fixes: 2bff3916fda9 ("usb: musb: Fix PM for hub disconnect")
Cc: stable <sta...@vger.kernel.org>     # 4.9
Cc: Tony Lindgren <t...@atomide.com>
Signed-off-by: Johan Hovold <jo...@kernel.org>
---
 drivers/usb/musb/musb_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 8645432337cb..8c40fc555eb0 100644
--- a/drivers/usb/musb/musb_core.c
+++ b/drivers/usb/musb/musb_core.c
@@ -1861,22 +1861,22 @@ static void musb_pm_runtime_check_session(struct musb 
*musb)
                MUSB_DEVCTL_HR;
        switch (devctl & ~s) {
        case MUSB_QUIRK_B_INVALID_VBUS_91:
-               if (musb->quirk_retries--) {
+               if (musb->quirk_retries) {
                        musb_dbg(musb,
                                 "Poll devctl on invalid vbus, assume no 
session");
                        schedule_delayed_work(&musb->irq_work,
                                              msecs_to_jiffies(1000));
-
+                       musb->quirk_retries--;
                        return;
                }
                /* fall through */
        case MUSB_QUIRK_A_DISCONNECT_19:
-               if (musb->quirk_retries--) {
+               if (musb->quirk_retries) {
                        musb_dbg(musb,
                                 "Poll devctl on possible host mode 
disconnect");
                        schedule_delayed_work(&musb->irq_work,
                                              msecs_to_jiffies(1000));
-
+                       musb->quirk_retries--;
                        return;
                }
                if (!musb->session)
-- 
2.14.1

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