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  • Lu Baolu's avatar
    usb: core: lpm: add sysfs node for usb3 lpm permit · 513072d9
    Lu Baolu authored
    
    
    USB3 LPM is default on in Linux kernel if both xHCI host controller
    and the USB devices declare to be LPM-capable. Unfortunately, some
    devices are known to work well with LPM disabled, but to be broken
    if LPM is enabled, although it declares the LPM capability.  Users
    won't be able to use this kind of devices, until someone puts them
    in the kernel blacklist and gets the kernel upgraded.
    
    This patch adds a sysfs node to permit or forbit USB3 LPM U1 or U2
    entry for a port. The settings apply to both before and after device
    enumeration. Supported values are "0" - neither u1 nor u2 permitted,
    "u1" - only u1 is permitted, "u2" - only u2 is permitted, "u1_u2" -
    both u1 and u2 are permitted. With this interface, users can use an
    LPM-unfriendly USB device on a released Linux kernel.
    
    Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
    Signed-off-by: default avatarZhuang Jin Can <jin.can.zhuang@intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    513072d9