• Alan Stern's avatar
    USB: add missing delay during remote wakeup · 49d0f078
    Alan Stern authored
    This patch (as1330) fixes a bug in khbud's handling of remote
    wakeups.  When a device sends a remote-wakeup request, the parent hub
    (or the host controller driver, for directly attached devices) begins
    the resume sequence and notifies khubd when the sequence finishes.  At
    this point the port's SUSPEND feature is automatically turned off.
    
    However the device needs an additional 10-ms resume-recovery time
    (TRSMRCY in the USB spec).  Khubd does not wait for this delay if the
    SUSPEND feature is off, and as a result some devices fail to behave
    properly following a remote wakeup.  This patch adds the missing
    delay to the remote-wakeup path.
    
    It also extends the resume-signalling delay used by ehci-hcd and
    uhci-hcd from 20 ms (the value in the spec) to 25 ms (the value we use
    for non-remote-wakeup resumes).  The extra time appears to help some
    devices.
    Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Cc: stable <stable@kernel.org>
    Cc: Rickard Bellini <rickard.bellini@ericsson.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    
    49d0f078
uhci-hub.c 10.9 KB