Re: [RFC][PATCH] cpufreq: User/admin documentation update and consolidation
From: Viresh Kumar
Date: Mon Feb 20 2017 - 04:56:28 EST
On 18-02-17, 02:36, Rafael J. Wysocki wrote:
> +CPU Initialization
> +Next, the scaling driver's ``->init()`` callback is invoked with the policy
> +pointer of the new CPU passed to it as the argument. If the policy object
> +pointed to by it is new
The callbacks don't need to do anything special for a new policy.
Infact, ->init() is only called for new policies or policies which
don't have any active CPUs as of now.
> , that callback is expected to initialize the performance
> +scaling hardware interface for the given CPU (or, more precisely, for the set of
> +CPUs sharing the hardware interface it belongs to, represented by its policy
> +object) and to set parameters of the policy, like the minimum and maximum
> +frequencies supported by the hardware, the table of available frequencies (if
> +the set of supported P-states is not a continuous range), and the mask of CPUs
> +that belong to the same policy.
Maybe we should explicitly mention that both online and offline CPUs
should be set in the mask ?
> That mask is then used by the core to populate
> +the policy pointers for all of the CPUs in it.
> +The next major initialization step for a new policy object is to attach a
> +scaling governor to it (to begin with, that is the default scaling governor
> +determined by the kernel configuration, but it may be changed later
> +via ``sysfs``). First, a pointer to the new policy object is passed to the
> +governor's ``->init()`` callback which is expected to initialize all of the
> +data structures necessary to handle the given policy and, possibly, to add
> +a governor ``sysfs`` interface to it. Next, the governor is started by
> +invoking its ``->start()`` callback.
The rest of it looked good. Nice work Rafael :)
Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>