• Huang Rui's avatar
    usb: core: implement AMD remote wakeup quirk · 7868943d
    Huang Rui authored
    The following patch is required to resolve remote wake issues with
    certain devices.
    
    Issue description:
    If the remote wake is issued from the device in a specific timing
    condition while the system is entering sleep state then it may cause
    system to auto wake on subsequent sleep cycle.
    
    Root cause:
    Host controller rebroadcasts the Resume signal > 100 µseconds after
    receiving the original resume event from the device. For proper
    function, some devices may require the rebroadcast of resume event
    within the USB spec of 100µS.
    
    Workaroud:
    1. Filter the AMD platforms with Yangtze chipset, then judge of all the usb
    devices are mouse or not. And get out the port id which attached a mouse
    with Pixart controller.
    2. Then reset the port which attached issue device during system resume
    from S3.
    
    [Q] Why the special devices are only mice? Would high speed devices
    such as 3G modem or USB Bluetooth adapter trigger this issue?
    - Current this sensitivity is only confined to devices that use Pixart
      controllers. This controller is designed for use with LS mouse
    devices only. We have not observed any other devices failing. There
    may be a small risk for other devices also but this patch (reset
    device in resume phase) will cover the cases if required.
    
    [Q] Shouldn’t the resume signal be sent within 100 us for every
    device?
    - The Host controller may not send the resume signal within 100us,
      this our host controller specification change. This is why we
    require the patch to prevent side effects on certain known devices.
    
    [Q] Why would clicking mouse INTENSELY to wake the system up trigger
    this issue?
    - This behavior is specific to the devices that use Pixart controller.
      It is timing dependent on when the resume event is triggered during
    the sleep state.
    
    [Q] Is it a host controller issue or mouse?
    - It is the host controller behavior during resume that triggers the
      device incorrect behavior on the next resume.
    
    This patch sets USB_QUIRK_RESET_RESUME flag for these Pixart-based mice
    when they attached to platforms with AMD Yangtze chipset.
    Signed-off-by: default avatarHuang Rui <ray.huang@amd.com>
    Suggested-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Acked-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Acked-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    7868943d
hcd-pci.c 17.3 KB