From: Jiri Kosina There is a problem in th following scenario(s): boot -> suspend -> (un)plug battery -> resume The problem arises in both cases - i.e. suspend with battery plugged in, and resume with battery unplugged, or vice versa. After resume, when the battery status has changed (plugged in -> unplegged or unplugged -> plugged in) during the time when the system was sleeping, the /proc/acpi/battery/*/* is wrong (showing the state before suspend, not the current state). The following patch adds ->resume method to the ACPI battery handler, which has the only aim - to check whether the battery state has changed during sleep, and if so, update the ACPI internal data structures, so that information published through /proc/acpi/battery/*/* is correct even after suspend/resume cycle, during which the battery was removed/inserted. The patch is against current ACPI git tree, but applies cleanly also against -mm and probably other trees. Please apply. Signed-off-by: Jiri Kosina Cc: "Brown, Len" Signed-off-by: Andrew Morton --- drivers/acpi/battery.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff -puN drivers/acpi/battery.c~acpi-preserve-correct-battery-state-through-suspend-resume-cycles drivers/acpi/battery.c --- a/drivers/acpi/battery.c~acpi-preserve-correct-battery-state-through-suspend-resume-cycles +++ a/drivers/acpi/battery.c @@ -64,6 +64,7 @@ extern void *acpi_unlock_battery_dir(str static int acpi_battery_add(struct acpi_device *device); static int acpi_battery_remove(struct acpi_device *device, int type); +static int acpi_battery_resume(struct acpi_device *device, int status); static struct acpi_driver acpi_battery_driver = { .name = ACPI_BATTERY_DRIVER_NAME, @@ -71,6 +72,7 @@ static struct acpi_driver acpi_battery_d .ids = ACPI_BATTERY_HID, .ops = { .add = acpi_battery_add, + .resume = acpi_battery_resume, .remove = acpi_battery_remove, }, }; @@ -753,6 +755,19 @@ static int acpi_battery_remove(struct ac return 0; } +/* this is needed to learn about changes made in suspended state */ +static int acpi_battery_resume(struct acpi_device *device, int state) +{ + struct acpi_battery *battery; + + if (!device) + return -EINVAL; + + battery = (struct acpi_battery *)device->driver_data; + return acpi_battery_check(battery); + +} + static int __init acpi_battery_init(void) { int result; _