linux/drivers/i2c
Lan Tianyu 40e7fcb192 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 <jan.brummer@tabos.org>
Tested-by: Adam Williamson <adamw@happyassassin.net>
Tested-by: Michael Shigorin <shigorin@gmail.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-11-24 01:04:55 +01:00
..
algos i2c: remove FSF address 2014-11-07 18:35:33 +01:00
busses i2c: at91: don't account as iowait 2014-11-07 18:56:31 +01:00
muxes Merge branch 'i2c/for-3.17' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux 2014-08-09 09:15:07 -07:00
i2c-boardinfo.c i2c: remove FSF address 2014-11-07 18:35:33 +01:00
i2c-core.c ACPI: Add _DEP support to fix battery issue on Asus T100TA 2014-11-24 01:04:55 +01:00
i2c-core.h i2c: remove FSF address 2014-11-07 18:35:33 +01:00
i2c-dev.c i2c: remove FSF address 2014-11-07 18:35:33 +01:00
i2c-mux.c i2c: mux: Inherit retry count and timeout from parent for muxed bus 2013-12-12 22:39:28 +01:00
i2c-smbus.c i2c: remove FSF address 2014-11-07 18:35:33 +01:00
i2c-stub.c i2c: remove FSF address 2014-11-07 18:35:33 +01:00
Kconfig i2c: rework kernel config I2C_ACPI 2014-08-19 10:19:39 -05:00
Makefile i2c: move acpi code back into the core 2014-09-25 16:07:15 +02:00