• Hans de Goede's avatar
    ACPI: scan: Fix battery devices sometimes never binding · 0f347aa0
    Hans de Goede authored
    With the new 2 step scanning process, which defers instantiating some
    ACPI-devices based on their _DEP to the second step, the following may
    happen:
    
    1. During the first acpi_walk_namespace(acpi_bus_check_add) call
       acpi_scan_check_dep() gets called on the Battery ACPI dev handle and
       adds one or more deps for this handle to the acpi_dep_list
    
    2. During the first acpi_bus_attach() call one or more of the suppliers of
       these deps get their driver attached and
       acpi_walk_dep_device_list(supplier_handle) gets called.
    
       At this point acpi_bus_get_device(dep->consumer) get called,
       but since the battery has DEPs it has not been instantiated during the
       first acpi_walk_namespace(acpi_bus_check_add), so the
       acpi_bus_get_device(dep->consumer) call fails.
    
       Before this commit, acpi_walk_dep_device_list() would now continue
       *without* removing the acpi_dep_data entry for this supplier,consumer
       pair from the acpi_dep_list.
    
    3. During the second acpi_walk_namespace(acpi_bus_check_add) call
       an acpi_device gets instantiated for the battery and
       acpi_scan_dep_init() gets called to initialize its dep_unmet val.
    
       Before this commit, the dep_unmet count would include DEPs for
       suppliers for which acpi_walk_dep_device_list(supplier_handle)
       has already been called, so it will never become 0 and the
       ACPI battery driver will never get attached / bind.
    
    Fix the ACPI battery driver never binding in this scenario by making
    acpi_walk_dep_device_list() always remove matching acpi_dep_data
    entries independent of the acpi_bus_get_device(dep->consumer) call
    succeeding or not.
    
    Fixes: 71da201f ("ACPI: scan: Defer enumeration of devices with _DEP lists")
    Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    0f347aa0
scan.c 61.5 KB