• Hans de Goede's avatar
    ACPI: scan: Do not increase dep_unmet for already met dependencies · d730192f
    Hans de Goede authored
    On the Toshiba Encore WT10-A tablet the BATC battery ACPI device depends
    on 3 other devices:
    
                Name (_DEP, Package (0x03)  // _DEP: Dependencies
                {
                    I2C1,
                    GPO2,
                    GPO0
                })
    
    acpi_scan_check_dep() adds all 3 of these to the acpi_dep_list and then
    before an acpi_device is created for the BATC handle (and thus before
    acpi_scan_dep_init() runs) acpi_scan_clear_dep() gets called for both
    GPIO depenencies, with free_when_met not set for the dependencies.
    
    Since there is no adev for BATC yet, there also is no dep_unmet to
    decrement. The only result of acpi_scan_clear_dep() in this case is
    dep->met getting set.
    
    Soon after acpi_scan_clear_dep() has been called for the GPIO dependencies
    the acpi_device gets created for the BATC handle and acpi_scan_dep_init()
    runs, this sees 3 dependencies on the acpi_dep_list and initializes
    unmet_dep to 3. Later when the dependency for I2C1 is met unmet_dep
    becomes 2, but since the 2 GPIO deps where already met it never becomes 0
    causing battery monitoring to not work.
    
    Fix this by modifying acpi_scan_dep_init() to not increase dep_met for
    dependencies which have already been marked as being met.
    
    Fixes: 3ba12d8d ("ACPI: scan: Reduce overhead related to devices with dependencies")
    Signed-off-by: default avatarHans de Goede <hdegoede@redhat.com>
    Cc: 6.5+ <stable@vger.kernel.org> # 6.5+
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    d730192f
scan.c 70.4 KB