Re: [PATCH] cpufreq: acpi_cpufreq: base frequency attribute support

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Fri, 2016-02-26 at 07:27 +0530, Viresh Kumar wrote:
> On 25-02-16, 10:07, Srinivas Pandruvada wrote:
> > If I use cpufreq_driver.attr, then it will create sysfs attribute
> > for
> > every system using acpi-cpufreq, whether they can support it or
> > not.
> > This change is only needed for the later generation of Intel CPUs
> > (IvyBridge and later). 
> > There is no standard ACPI way to know the base frequency if we add
> > attribute for all systems using acpi-cpufreq.
> 
> Why can't you set cpufreq_driver.attr selectively from probe()?
> 
We are setting a cpufreq global variable in cpufreq_driver->attr with
this for each cpu. This feature can be absent in certain cpus. So
unlike boost it is not system wide, so I have to reset the attr to NULL
for some cpus.
Can we assume that cpufreq_driver->init(policy) calls are always
serialized from cpu online/offline and subsys_interface callback path?

Thanks,
Srinivas
> See below for reference.
> 
> commit 21c36d35711d ("cpufreq-dt: make scaling_boost_freqs sysfs attr
> available
> when boost is enabled")
>