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authorDaniel Kurtz <djkurtz@chromium.org>2011-11-17 19:23:49 +0800
committerJiri Kosina <jkosina@suse.cz>2011-12-21 11:18:35 +0100
commitf0befcd64bc57e6a0b7a96c37c55f79e6b999af7 (patch)
treef6847dbd4cf25e0f8ae21707bb365424ba5e1816 /drivers/hid/hid-ezkey.c
parentede6a8b239736acd55ad8a219b2bd2ae7f551fb7 (diff)
HID: usbhid: hid-core: submit queued urbs before suspend
If any userspace program has opened a keyboard device, the input core de-activates the keyboard's LEDs upon suspend(). It does this by sending individual EV_LED[LED_X]=0 events to the underlying device driver by directly calling the driver's registered event() handler. The usb-hid driver event() handler processes each request by immediately attempting to submit a CTRL URB to turn off the LED. USB URB submission is asynchronous. First the URB is added to the head of the ctrl queue. Then, if the CTRL_RUNNING flag is false, the URB is submitted immediately (and CTRL_RUNNING is set). If the CTRL_RUNNING flag was already true, then the newly queued URB is submitted in the ctrl completion handler when all previously submitted URBs have completed. When all queued URBs have been submitted, the completion handler clears the CTRL_RUNNING flag. In the 2-LED suspend case, at input suspend(), 2 LED event CTRL URBs get queued, with only the first actually submitted. Soon after input suspend() handler finishes, the usb-hid suspend() handler gets called. Since this is NOT a PM_EVENT_AUTO suspend, the handler sets REPORTED_IDLE, then waits for io to complete. Unfortunately, this usually happens while the first LED request is actually still being processed. Thus when the completion handler tries to submit the second LED request it fails, since REPORTED_IDLE is already set! This REPORTED_IDLE check failure causes the completion handler to complete, however without clearing the CTRL_RUNNING flag. This, in turn, means that the suspend() handler's wait_io() condition is never satisfied, and instead it times out after 10 seconds, aborting the original system suspend. This patch changes the behavior to the following: (1) allow completion handler to finish submitting all queued URBs, even if REPORTED_IDLE is set. This guarantees that all URBs queued before the hid-core suspend() call will be submitted before the system is suspended. (2) if REPORTED_IDLE is set and the URB queue is empty, queue, but don't submit, new URB submission requests. These queued requests get submitted when resume() flushes the URB queue. This is similar to the existing behavior, however, any requests that arrive while the queue is not yet empty will still get submitted before suspend. (3) set the RUNNING flag when flushing the URB queue in resume(). This keeps URBs that were queued in (2) from colliding with any new URBs that are being submitted during the resume process. The new URB submission requests upon resume get properly queued behind the ones being flushed instead of the current situation where they collide, causing memory corruption and oopses. Signed-off-by: Daniel Kurtz <djkurtz@chromium.org> Acked-by: Oliver Neukum <oneukum@suse.de> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid/hid-ezkey.c')
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