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    SubjectRe: [PATCH] ACPI / Battery: Return -ENODATA for unknown values in get_property()
    On Sat, Oct 23, 2010 at 12:19:13AM +0200, Rafael J. Wysocki wrote:
    > OK, so can you test the patch below, please?

    The latest patch seems to fix/workaround the problem. upower now reports
    0 as the energy rate, there are no warnings in dmesg and battery hotplug
    works. Looks good and there's the option for a future upower to
    interpret the missing sysfs as meaning "unknown".

    Tested-by: Sitsofe Wheeler <>

    > The function acpi_battery_get_property() is called by the
    > power supply framework's function power_supply_show_property()
    > implementing the sysfs interface for power supply devices as the
    > ACPI battery driver's ->get_property() callback. Thus it is supposed
    > to return error code if the value of the given property is unknown.
    > Unfortunately, however, it returns 0 in those cases and puts a
    > wrong (negative) value into the intval field of the
    > union power_supply_propval object provided by
    > power_supply_show_property(). In consequence, wron negative

    wron -> wrong?

    > Fix this by making acpi_battery_get_property() return -ENODEV
    > for properties with unknown values (-ENODEV is returned, because
    > power_supply_uevent() returns with error for any other error code
    > returned by power_supply_show_property()).

    OK that's sneaky and clever - technically power_supply_uevent should be
    more robust but presumably things are already prepared to handle -ENODEV
    so overloading the meaning leads to the smallest change.

    Sitsofe |

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