diff options
author | Alan Stern <stern@rowland.harvard.edu> | 2020-04-22 16:09:51 -0400 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-04-29 16:33:13 +0200 |
commit | 50ad463e20bf419a9b3d058ae792b920f363b9e3 (patch) | |
tree | 978677ee7e34b674d0ace2c085212223252ff655 /Documentation | |
parent | b48193a7c303272d357b27dd7d72cbf89f7b2d35 (diff) |
USB: hub: Fix handling of connect changes during sleep
commit 9f952e26295d977dbfc6fedeaf8c4f112c818d37 upstream.
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 'Documentation')
0 files changed, 0 insertions, 0 deletions