On Dell Latitude C600 laptop with Pentium 3 850MHz processor, the
speedstep-smi driver sometimes loads and sometimes doesn't load with
"change to state X failed" message.

The hardware sometimes refuses to change frequency and in this case, we
need to retry later. I found out that we need to enable interrupts while
waiting. When we enable interrupts, the hardware blockage that prevents
frequency transition resolves and the transition is possible. With
disabled interrupts, the blockage doesn't resolve (no matter how long do
we wait). The exact reasons for this hardware behavior are unknown.

This patch enables interrupts in the function speedstep_set_state that can
be called with disabled interrupts. However, this function is called with
disabled interrupts only from speedstep_get_freqs, so it shouldn't cause
any problem.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com
Cc: All applicable <stable@vger.kernel.org>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Pull SFI-based cpufreq driver for v3.20 from Len Brown.

* 'sfi' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux:
  cpufreq: Add SFI based cpufreq driver support
  SFI: fix compiler warnings

Allow users the option to disable the driver for any hardware
which does not support HWP.
Signed-off-by: NKristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The cpufreq_cooling_unregister() function tests whether its argument is NULL
and then returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
[ rjw: Subject ]
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

To make code more readable and less error prone, lets create a helper macro for
iterating over all available governors.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Acked-by: NSaravana Kannan <skannan@codeaurora.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

To make code more readable and less error prone, lets create a helper macro for
iterating over all active policies.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

When cpufreq is disabled, the per-cpu variable would have been set to
NULL. Remove this unnecessary check.

[ Changelog from Saravana Kannan. ]
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Acked-by: NSaravana Kannan <skannan@codeaurora.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

In __cpufreq_remove_dev_finish(), per-cpu 'cpufreq_cpu_data' needs
to be cleared before calling kobject_put(&policy->kobj) and under
cpufreq_driver_lock. Otherwise, if someone else calls cpufreq_cpu_get()
in parallel with it, they can obtain a non-NULL policy from that after
kobject_put(&policy->kobj) was executed.

Consider this case:

Thread A				Thread B
cpufreq_cpu_get()
  acquire cpufreq_driver_lock
  read-per-cpu cpufreq_cpu_data
					kobject_put(&policy->kobj);
  kobject_get(&policy->kobj);
					...
					per_cpu(&cpufreq_cpu_data, cpu) = NULL

And this will result in a warning like this one:

 ------------[ cut here ]------------
 WARNING: CPU: 0 PID: 4 at include/linux/kref.h:47
 kobject_get+0x41/0x50()
 Modules linked in: acpi_cpufreq(+) nfsd auth_rpcgss nfs_acl
 lockd grace sunrpc xfs libcrc32c sd_mod ixgbe igb mdio ahci hwmon
 ...
 Call Trace:
  [<ffffffff81661b14>] dump_stack+0x46/0x58
  [<ffffffff81072b61>] warn_slowpath_common+0x81/0xa0
  [<ffffffff81072c7a>] warn_slowpath_null+0x1a/0x20
  [<ffffffff812e16d1>] kobject_get+0x41/0x50
  [<ffffffff815262a5>] cpufreq_cpu_get+0x75/0xc0
  [<ffffffff81527c3e>] cpufreq_update_policy+0x2e/0x1f0
  [<ffffffff810b8cb2>] ? up+0x32/0x50
  [<ffffffff81381aa9>] ? acpi_ns_get_node+0xcb/0xf2
  [<ffffffff81381efd>] ? acpi_evaluate_object+0x22c/0x252
  [<ffffffff813824f6>] ? acpi_get_handle+0x95/0xc0
  [<ffffffff81360967>] ? acpi_has_method+0x25/0x40
  [<ffffffff81391e08>] acpi_processor_ppc_has_changed+0x77/0x82
  [<ffffffff81089566>] ? move_linked_works+0x66/0x90
  [<ffffffff8138e8ed>] acpi_processor_notify+0x58/0xe7
  [<ffffffff8137410c>] acpi_ev_notify_dispatch+0x44/0x5c
  [<ffffffff8135f293>] acpi_os_execute_deferred+0x15/0x22
  [<ffffffff8108c910>] process_one_work+0x160/0x410
  [<ffffffff8108d05b>] worker_thread+0x11b/0x520
  [<ffffffff8108cf40>] ? rescuer_thread+0x380/0x380
  [<ffffffff81092421>] kthread+0xe1/0x100
  [<ffffffff81092340>] ? kthread_create_on_node+0x1b0/0x1b0
  [<ffffffff81669ebc>] ret_from_fork+0x7c/0xb0
  [<ffffffff81092340>] ? kthread_create_on_node+0x1b0/0x1b0
 ---[ end trace 89e66eb9795efdf7 ]---

The actual code flow is as follows:

 Thread A: Workqueue: kacpi_notify

 acpi_processor_notify()
   acpi_processor_ppc_has_changed()
         cpufreq_update_policy()
           cpufreq_cpu_get()
             kobject_get()

 Thread B: xenbus_thread()

 xenbus_thread()
   msg->u.watch.handle->callback()
     handle_vcpu_hotplug_event()
       vcpu_hotplug()
         cpu_down()
           __cpu_notify(CPU_POST_DEAD..)
             cpufreq_cpu_callback()
               __cpufreq_remove_dev_finish()
                 cpufreq_policy_put_kobj()
                   kobject_put()

cpufreq_cpu_get() gets the policy from per-cpu variable cpufreq_cpu_data
under cpufreq_driver_lock, and once it gets a valid policy it expects it
to not be freed until cpufreq_cpu_put() is called.

But the race happens when another thread puts the kobject first and updates
cpufreq_cpu_data before or later. And so the first thread gets a valid policy
structure and before it does kobject_get() on it, the second one has already
done kobject_put().

Fix this by setting cpufreq_cpu_data to NULL before putting the kobject and that
too under locks.
Reported-by: NEthan Zhao <ethan.zhao@oracle.com>
Reported-by: NSantosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Cc: 3.12+ <stable@vger.kernel.org> # 3.12+
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

If the user has requested an override of the min_perf_pct via
sysfs, then it should be restored whenever policy is updated,
such as on resume.  Take the max of whatever the user requested
and whatever the policy is.
Signed-off-by: NKristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

When thermal or other subsystem requests to change the policy,
use that irrepective of whether cpufreq policy is PERFORMANCE or
not. Without this change, when thermal subsystem passive policy wants
to reduce performance, it still runs at 100%.
Signed-off-by: NSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: NKristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Add a sysfs interface to display the total number of supported
pstates.  This value is independent of whether turbo has been
enabled or disabled.
Signed-off-by: NKristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

This patch adds "turbo_pct" to the intel_pstate sysfs interface.
turbo_pct will display the percentage of the total supported
pstates that are in the turbo range.  This value is independent
of whether turbo has been disabled or not.
Signed-off-by: NKristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Add SKL cpuid.
Signed-off-by: NKristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There is no possibility of any race on updating last_index, trans_table or
total_trans as these are updated only by cpufreq_stat_notifier_trans() which
will be called sequentially.

The only place where locking is still relevant is: cpufreq_stats_update(), which
updates time_in_state and last_time. This can be called by two thread in
parallel, that may result in races.

The two threads being:
- sysfs read of time_in_state
- and frequency transition that calls cpufreq_stat_notifier_trans().

Remove locking from the first case mentioned above.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

We need to call cpufreq_stats_update() to update 'time_in_state' for the last
frequency. This is achieved by calling it from cpufreq_stat_notifier_trans(),
which is called after frequency transition.

But if we detect that the cpu's frequency haven't really changed and its a false
POSTCHANGE notification, we don't really need to update time_in_state.

It wouldn't cause any harm in calling cpufreq_stats_update() but we can avoid
calling it here and call it when the frequency really changes. The result will
be the same but more efficient.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

cpufreq_stats_update() updates time_in_state and nothing else. It should ideally
be updated only in two cases:
- User requested for the current value of time_in_state.
- We have switched states and so need to update time for the last state.

Currently, we are also doing this while user asks for the transition table of
frequencies. It wouldn't do any harm, but no good as well. Its useless here.

Remove it.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

'time_in_state' can't be NULL if 'stats' is valid. These are allocated together
and only if time_in_state is allocated successfully, we update policy->stats.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Userspace is free to read value of any file from cpufreq/stats directory once
they are created. __cpufreq_stats_create_table() is creating the sysfs files
first and then allocating resources for them. Though it would be quite difficult
to trigger the racy situation here, but for the sake of keeping sensible code
lets create sysfs entries only after we are ready to go.

This also does some makeup to the routine to make it look better.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

CPUFREQ_UPDATE_POLICY_CPU notifications were used only from cpufreq-stats which
doesn't use it anymore. Remove them.

This also decrements values of other notification macros defined after
CPUFREQ_UPDATE_POLICY_CPU by 1 to remove gaps. Hopefully all users are using
macro's instead of direct numbers and so they wouldn't break as macro values are
changed now.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

'cpu' field of struct cpufreq_stats isn't used anymore and so can be dropped.
This change makes cpufreq_stats_update_policy_cpu() empty and so that is removed
as well.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

'last_cpu' was used only from cpufreq-stats and isn't used anymore. Get rid of
it.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Currently we name objects of 'struct cpufreq_stats' as 'stat' and 'stats'.
Use 'stats' to make it consistent.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

All CPUs sharing a cpufreq policy share stats too. For this reason,
add a stats pointer to struct cpufreq_policy and drop per-CPU variable
cpufreq_stats_table used for accessing cpufreq stats so as to reduce
code complexity.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

It is better to pass a struct cpufreq_stats pointer to cpufreq_stats_update()
instead of a CPU number, because that's all it needs.

Even if we pass a cpu number to cpufreq_stats_update(), it reads the per-cpu
variable to get 'stats' out of it. So we are doing these operations
unnecessarily:
- First getting the cpu number to pass to cpufreq_stats_update(), stat->cpu.
- And then getting stats from the cpu, per_cpu(cpufreq_stats_table, cpu).
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

While we allocate stats, we do need to check if freq-table is present
or not as we need to use it then. But while freeing stats, all we need
to know is if stats holds a valid pointer value. There is no use of
testing if cpufreq table is present or not.

Don't check it.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

'cur_time' is defined in the first line and is then assigned a value
in the next line. Initialize it while defining it.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

It was never used, but is there since the first commit. Remove it.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

__cpufreq_stats_create_table() is called from:

- cpufreq notifier on creation of a new policy. Stats will always be
  NULL here.
- cpufreq_stats_init() for all CPUs as cpufreq-stats might have been
  initialized after cpufreq driver. For any policy, 'stats' will be
  NULL for the first CPU only and will be valid for all other CPUs
  managed by the same policy.

While we return for other CPUs, we don't return the right error value.
It's not that we would fail with -EBUSY. But generally, this is what
these return values mean:
- EBUSY: we are busy right now, try again. And the retry attempt might
  be immediate.
- EEXIST: We already have what you are trying to create and there is no
  need to create it again, and so no more tries are required.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

The MODULE_DESCRIPTION() string is just too long and then is broken into
multiple lines just to make checkpatch happy.

Rewrite it to make it more precise.
Reviewed-by: NPrarit Bhargava <prarit@redhat.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

We need to initialize completion and work only on policy allocation and not
really on the policy restore side and so we better move this piece of code to
cpufreq_policy_alloc().
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

CPUFREQ_STICKY flag is set by drivers which don't want to get unregistered
even if cpufreq-core isn't able to initialize policy for any CPU.

When this flag isn't set, we try to unregister the driver. To find out
which CPUs are registered and which are not, we try to check per_cpu
cpufreq_cpu_data for all CPUs. Because we have a list of valid policies
available now, we better check if the list is empty or not instead of
the 'for' loop. That will be much more efficient.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

These variables are just used within adjust_jiffies() and so must be
local to it. Also there is no need of a dummy routine for CONFIG_SMP
case as we can take care of all that with help of macros in the same
routine. It doesn't look that ugly.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

We just need to check if a 'policy' is already present for the cpu we are
adding. We don't need to take all the locks and do kobject usage updates. Use
the light-weight cpufreq_cpu_get_raw() routine instead.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There is no need of this separate variable, use 'policy' instead.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

These are messing up more than the benefit they provide. It isn't
a lot of code anyway, that we will compile without them.

Kill them.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

We should first check if a cpufreq driver is already registered or not
before updating driver_data->flags.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There is no point finding out the 'policy' again within __cpufreq_get()
when all the callers already have it. Just make them pass policy instead.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

There is no point finding out the 'policy' again within cpufreq_out_of_sync()
when all the callers already have it. Just make them pass policy instead.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Either we can be setpolicy or target type, nothing else. And so the
else part of setpolicy will automatically be of has_target() type.
And so we don't need to check it again.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

Remove unnecessary from find_governor's name.
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>