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| author | Alan Stern <stern@rowland.harvard.edu> | 2020-04-22 16:09:51 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-04-23 15:22:41 +0200 |
| commit | 9f952e26295d977dbfc6fedeaf8c4f112c818d37 (patch) | |
| tree | 7bba4ea8fe10c215634f35128b21807ae3fc05b7 /drivers/usb/core/hub.c | |
| parent | 0df9433fcae02215c8fd79690c134d535c7bb905 (diff) | |
| download | linux-9f952e26295d977dbfc6fedeaf8c4f112c818d37.tar.bz2 | |
USB: hub: Fix handling of connect changes during sleep
Commit 8099f58f1ecd ("USB: hub: Don't record a connect-change event
during reset-resume") wasn't very well conceived. The problem it
tried to fix was that if a connect-change event occurred while the
system was asleep (such as a device disconnecting itself from the bus
when it is suspended and then reconnecting when it resumes)
requiring a reset-resume during the system wakeup transition, the hub
port's change_bit entry would remain set afterward. This would cause
the hub driver to believe another connect-change event had occurred
after the reset-resume, which was wrong and would lead the driver to
send unnecessary requests to the device (which could interfere with a
firmware update).
The commit tried to fix this by not setting the change_bit during the
wakeup. But this was the wrong thing to do; it means that when a
device is unplugged while the system is asleep, the hub driver doesn't
realize anything has happened: The change_bit flag which would tell it
to handle the disconnect event is clear.
The commit needs to be reverted and the problem fixed in a different
way. Fortunately an alternative solution was noted in the commit's
Changelog: We can continue to set the change_bit entry in
hub_activate() but then clear it when a reset-resume occurs. That way
the the hub driver will see the change_bit when a device is
disconnected but won't see it when the device is still present.
That's what this patch does.
Reported-and-tested-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Fixes: 8099f58f1ecd ("USB: hub: Don't record a connect-change event during reset-resume")
Tested-by: Paul Zimmerman <pauldzim@gmail.com>
CC: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.2004221602480.11262-100000@iolanthe.rowland.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/core/hub.c')
| -rw-r--r-- | drivers/usb/core/hub.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 54cd8ef795ec..83549f009ced 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -1223,6 +1223,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type) #ifdef CONFIG_PM udev->reset_resume = 1; #endif + /* Don't set the change_bits when the device + * was powered off. + */ + if (test_bit(port1, hub->power_bits)) + set_bit(port1, hub->change_bits); } else { /* The power session is gone; tell hub_wq */ @@ -3088,6 +3093,15 @@ static int check_port_resume_type(struct usb_device *udev, if (portchange & USB_PORT_STAT_C_ENABLE) usb_clear_port_feature(hub->hdev, port1, USB_PORT_FEAT_C_ENABLE); + + /* + * Whatever made this reset-resume necessary may have + * turned on the port1 bit in hub->change_bits. But after + * a successful reset-resume we want the bit to be clear; + * if it was on it would indicate that something happened + * following the reset-resume. + */ + clear_bit(port1, hub->change_bits); } return status; |