From 40e7fcb19293cbdff02c74cb0668413480f82ea1 Mon Sep 17 00:00:00 2001 From: Lan Tianyu Date: Sun, 23 Nov 2014 21:22:54 +0800 Subject: ACPI: Add _DEP support to fix battery issue on Asus T100TA ACPI 5.0 introduces _DEP (Operation Region Dependencies) to designate device objects that OSPM should assign a higher priority in start ordering due to future operation region accesses. On Asus T100TA, ACPI battery info are read from a I2C slave device via I2C operation region. Before I2C operation region handler is installed, battery _STA always returns 0. There is a _DEP method of designating start order under battery device node. This patch is to implement _DEP feature to fix battery issue on the Asus T100TA. Introducing acpi_dep_list and adding dep_unmet count in struct acpi_device. During ACPI namespace scan, create struct acpi_dep_data for a valid pair of master (device pointed to by _DEP)/ slave(device with _DEP), record master's and slave's ACPI handle in it and put it into acpi_dep_list. The dep_unmet count will increase by one if there is a device under its _DEP. Driver's probe() should return EPROBE_DEFER when find dep_unmet is larger than 0. When I2C operation region handler is installed, remove all struct acpi_dep_data on the acpi_dep_list whose master is pointed to I2C host controller and decrease slave's dep_unmet. When dep_unmet decreases to 0, all _DEP conditions are met and then do acpi_bus_attach() for the device in order to resolve battery _STA issue on the Asus T100TA. Link: https://bugzilla.kernel.org/show_bug.cgi?id=69011 Tested-by: Jan-Michael Brummer Tested-by: Adam Williamson Tested-by: Michael Shigorin Acked-by: Wolfram Sang Acked-by: Mika Westerberg Signed-off-by: Lan Tianyu Signed-off-by: Rafael J. Wysocki --- drivers/acpi/battery.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'drivers/acpi/battery.c') diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c index 8ec8a89a20ab..d98ba4355819 100644 --- a/drivers/acpi/battery.c +++ b/drivers/acpi/battery.c @@ -1180,6 +1180,10 @@ static int acpi_battery_add(struct acpi_device *device) if (!device) return -EINVAL; + + if (device->dep_unmet) + return -EPROBE_DEFER; + battery = kzalloc(sizeof(struct acpi_battery), GFP_KERNEL); if (!battery) return -ENOMEM; -- cgit v1.2.3