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

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

On Thu, 2016-02-25 at 10:07 -0800, Srinivas Pandruvada wrote:
> On Thu, 2016-02-25 at 08:57 +0530, Viresh Kumar wrote:
> > On 24-02-16, 15:37, Srinivas Pandruvada wrote:
> > > Good I tested again.
> > > 
> > > Hi Viresh,
> > > 
> > > Are we no longer allowed to call
> > > 	sysfs_create_file in cpufreq_driver.init() callback?
> > > 
> > > The following call crashes because of BUG_ON for !kobj->sd:
> > > 	sysfs_create_file(&policy->kobj,
> > >                                  
> > > &(cpufreq_attr_base_frequency.attr));
> > > 
> > > Before I debug further, I want to check with you.
> > > This used to work before.
> > 
> > Haven't checked that yet, but you should be using
> > cpufreq_driver.attr
> > for this
> > kind of stuff, isn't it ?
> 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.
> 
There is used to be

cpufreq_policy_alloc() {
..
    ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
&dev>kobj, "cpufreq");
}

Now it is removed, so we don't have directory entry for policy->kobj to
add during init() callback. Now we have kobject_add after init()
callback returns for policy%u.

Thanks,
Srinivas