On Tuesday, November 25, 2014 08:18:34 AM Li, Aubrey wrote: > On 2014/11/24 23:27, Rafael J. Wysocki wrote: > > On Monday, November 24, 2014 10:39:55 AM Li, Aubrey wrote: > >> On 2014/11/23 21:22, Lan Tianyu wrote: > >>> ACPI 5.0 introduces _DEP 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 the 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. > >> > >> Well, Can we explicitly tied this up with ASUS T100TA in the code? > >> If I understand correctly, the assumption in the patch is that the > >> battery device only depends on I2C device, which is true on ASUS T100TA, > >> but may not on the other platforms. > >> > >> This patch does not work on a box I have, on it _DEP contains I2C and GPIO. > > > > Does the patch break anything for you? > > Not I'm aware so far. OK It is not a complete solution, but it is an improvement. It evidently helps people. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
