• Badhri Jagan Sridharan's avatar
    usb: typec: tcpm: Do not disconnect link for self powered devices · 5fca7488
    Badhri Jagan Sridharan authored
    [ Upstream commit 23b5f732 ]
    
    During HARD_RESET the data link is disconnected.
    For self powered device, the spec is advising against doing that.
    
    >From USB_PD_R3_0
    7.1.5 Response to Hard Resets
    Device operation during and after a Hard Reset is defined as follows:
    Self-powered devices Should Not disconnect from USB during a Hard Reset
    (see Section 9.1.2).
    Bus powered devices will disconnect from USB during a Hard Reset due to the
    loss of their power source.
    
    Tackle this by letting TCPM know whether the device is self or bus powered.
    
    This overcomes unnecessary port disconnections from hard reset.
    Also, speeds up the enumeration time when connected to Type-A ports.
    Signed-off-by: default avatarBadhri Jagan Sridharan <badhri@google.com>
    Reviewed-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
    ---------
    Version history:
    V3:
    Rebase on top of usb-next
    
    V2:
    Based on feedback from heikki.krogerus@linux.intel.com
    - self_powered added to the struct tcpm_port which is populated from
      a. "connector" node of the device tree in tcpm_fw_get_caps()
      b. "self_powered" node of the tcpc_config in tcpm_copy_caps
    
    Based on feedbase from linux@roeck-us.net
    - Code was refactored
    - SRC_HARD_RESET_VBUS_OFF sets the link state to false based
      on self_powered flag
    
    V1 located here:
    https://lkml.org/lkml/2018/9/13/94Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
    5fca7488
tcpm.h 5.74 KB