On Tue, Sep 25, 2012 at 12:43:54AM +0200, Daniel Lezcano wrote:
With the tegra3 and the big.LITTLE [1] new architectures, several cpus with different characteristics (latencies and states) can co-exists on the system.
The cpuidle framework has the limitation of handling only identical cpus.
This patch removes this limitation by introducing the multiple driver support for cpuidle.
This option is configurable at compile time and should be enabled for the architectures mentioned above. So there is no impact for the other platforms if the option is disabled. The option defaults to 'n'. Note the multiple drivers support is also compatible with the existing drivers, even if just one driver is needed, all the cpu will be tied to this driver using an extra small chunk of processor memory.
The multiple driver support use a per-cpu driver pointer instead of a global variable and the accessor to this variable are done from a cpu context.
In order to keep the compatibility with the existing drivers, the function 'cpuidle_register_driver' and 'cpuidle_unregister_driver' will register the specified driver for all the cpus.
The sysfs output for the 'current_driver' is changed when this option is set by giving the drivers per cpu.
eg. cpu0: acpi_idle cpu1: acpi_idle
Is this allowed? I thought sysfs files can output only 1 line of data?
Cheers,
Peter.