USB: musb: fix session-bit runtime-PM quirk

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 <stable@vger.kernel.org>     # 4.9
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
index 0296920..07b8c71 100644 (file)
--- 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)