Commit Graph

7 Commits

Author SHA1 Message Date
Shilpasri G Bhat cf30af7695 cpufreq: powernv: Set the cpus to nominal frequency during reboot/kexec
This patch ensures the cpus to kexec/reboot at nominal frequency.
Nominal frequency is the highest cpu frequency on PowerPC at
which the cores can run without getting throttled.

If the host kernel had set the cpus to a low pstate and then it
kexecs/reboots to a cpufreq disabled kernel it would cause the target
kernel to perform poorly. It will also increase the boot up time of
the target kernel. So set the cpus to high pstate, in this case to
nominal frequency before rebooting to avoid such scenarios.

The reboot notifier will set the cpus to nominal frequncy.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-29 15:53:04 +02:00
Preeti U Murthy b120339c78 cpufreq: powernv: Set the pstate of the last hotplugged out cpu in policy->cpus to minimum
Its possible today that the pstate of a core is held at a high even after the
entire core is hotplugged out if a load had just run on  the hotplugged cpu. This is
fair, since it is assumed that the pstate does not matter to a cpu in a deep idle
state, which is the expected state of a hotplugged core on powerpc. However on powerpc,
the pstate at a socket level is held at the maximum of the pstates of each core. Even
if the pstates of the active cores on that socket is low, the socket pstate is held
high due to the pstate of the hotplugged core in the above mentioned scenario. This
can cost significant amount of power loss for no good.

Besides, since it is a non active core, nothing can be done from the kernel's end
to set the frequency of the core right. Hence make use of the stop_cpu callback
to explicitly set the pstate of the core to a minimum when the last cpu of the
core gets hotplugged out.

Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-09-29 15:47:53 +02:00
Vaidyanathan Srinivasan 6174bac8c7 powerpc/cpufreq: Add pr_warn() on OPAL firmware failures
Cpufreq depends on platform firmware to implement PStates.  In case of
platform firmware failure, cpufreq should not panic host kernel with
BUG_ON().  Less severe pr_warn() will suffice.

Add firmware_has_feature(FW_FEATURE_OPALv3) check to
skip probing for device-tree on non-powernv platforms.

Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2014-08-05 15:40:41 +10:00
Brian Norris 60d1ea4e0a cpufreq: powernv: make local function static
powernv_cpufreq_get() is only referenced in this file.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org> on V2.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-05-17 01:25:46 +02:00
Srivatsa S. Bhat f3cae355a9 cpufreq, powernv: Fix build failure on UP
Paul Gortmaker reported the following build failure of the powernv cpufreq
driver on UP configs:

drivers/cpufreq/powernv-cpufreq.c:241:2: error: implicit declaration of
function 'cpu_sibling_mask' [-Werror=implicit-function-declaration]
cc1: some warnings being treated as errors
make[3]: *** [drivers/cpufreq/powernv-cpufreq.o] Error 1
make[2]: *** [drivers/cpufreq] Error 2
make[1]: *** [drivers] Error 2
make: *** [sub-make] Error 2

The trouble here is that cpu_sibling_mask is defined only in <asm/smp.h>,
and <linux/smp.h> includes <asm/smp.h> only in SMP builds.

So fix this build failure by explicitly including <asm/smp.h> in the driver,
so that we get the definition of cpu_sibling_mask even in UP configurations.

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-04-21 23:43:38 +02:00
Gautham R. Shenoy 0692c69138 cpufreq: powernv: Use cpufreq_frequency_table.driver_data to store pstate ids
The .driver_data field in the cpufreq_frequency_table was supposed to
be private to the drivers. However at some later point, it was being
used to indicate if the particular frequency in the table is the
BOOST_FREQUENCY. After patches [1] and [2], the .driver_data is once
again private to the driver. Thus we can safely use
cpufreq_frequency_table.driver_data to store pstate_ids instead of
having to maintain a separate array powernv_pstate_ids[] for this
purpose.

[1]:
  Subject: cpufreq: don't print value of .driver_data from core
  From   : Viresh Kumar <viresh.kumar@ linaro.org>
  url    : http://marc.info/?l=linux-pm&m=139601421504709&w=2

[2]:
  Subject: cpufreq: create another field .flags in cpufreq_frequency_table
  From   : Viresh Kumar <viresh.kumar@linaro.org>
  url    : http://marc.info/?l=linux-pm&m=139601416804702&w=2

Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-04-07 14:35:28 +02:00
Vaidyanathan Srinivasan b3d627a5f2 cpufreq: powernv: cpufreq driver for powernv platform
Backend driver to dynamically set voltage and frequency on
IBM POWER non-virtualized platforms.  Power management SPRs
are used to set the required PState.

This driver works in conjunction with cpufreq governors
like 'ondemand' to provide a demand based frequency and
voltage setting on IBM POWER non-virtualized platforms.

PState table is obtained from OPAL v3 firmware through device
tree.

powernv_cpufreq back-end driver would parse the relevant device-tree
nodes and initialise the cpufreq subsystem on powernv platform.

The code was originally written by svaidy@linux.vnet.ibm.com. Over
time it was modified to accomodate bug-fixes as well as updates to the
the cpu-freq core. Relevant portions of the change logs corresponding
to those modifications are noted below:

 * The policy->cpus needs to be populated in a hotplug-invariant
   manner instead of using cpu_sibling_mask() which varies with
   cpu-hotplug. This is because the cpufreq core code copies this
   content into policy->related_cpus mask which should not vary on
   cpu-hotplug. [Authored by srivatsa.bhat@linux.vnet.ibm.com]

 * Create a helper routine that can return the cpu-frequency for the
   corresponding pstate_id. Also, cache the values of the pstate_max,
   pstate_min and pstate_nominal and nr_pstates in a static structure
   so that they can be reused in the future to perform any
   validations. [Authored by ego@linux.vnet.ibm.com]

 * Create a driver attribute named cpuinfo_nominal_freq which creates
   a sysfs read-only file named cpuinfo_nominal_freq. Export the
   frequency corresponding to the nominal_pstate through this
   interface.

     Nominal frequency is the highest non-turbo frequency for the
   platform.  This is generally used for setting governor policies
   from user space for optimal energy efficiency. [Authored by
   ego@linux.vnet.ibm.com]

 * Implement a powernv_cpufreq_get(unsigned int cpu) method which will
   return the current operating frequency. Export this via the sysfs
   interface cpuinfo_cur_freq by setting powernv_cpufreq_driver.get to
   powernv_cpufreq_get(). [Authored by ego@linux.vnet.ibm.com]

[Change log updated by ego@linux.vnet.ibm.com]

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-04-07 14:35:27 +02:00