1. 30 Oct, 2013 1 commit
  2. 23 Apr, 2013 1 commit
    • Daniel Lezcano's avatar
      cpuidle: make a single register function for all · 4c637b21
      Daniel Lezcano authored
      The usual scheme to initialize a cpuidle driver on a SMP is:
      
      	cpuidle_register_driver(drv);
      	for_each_possible_cpu(cpu) {
      		device = &per_cpu(cpuidle_dev, cpu);
      		cpuidle_register_device(device);
      	}
      
      This code is duplicated in each cpuidle driver.
      
      On UP systems, it is done this way:
      
      	cpuidle_register_driver(drv);
      	device = &per_cpu(cpuidle_dev, cpu);
      	cpuidle_register_device(device);
      
      On UP, the macro 'for_each_cpu' does one iteration:
      
      #define for_each_cpu(cpu, mask)                 \
              for ((cpu) = 0; (cpu) < 1; (cpu)++, (void)mask)
      
      Hence, the initialization loop is the same for UP than SMP.
      
      Beside, we saw different bugs / mis-initialization / return code unchecked in
      the different drivers, the code is duplicated including bugs. After fixing all
      these ones, it appears the initialization pattern is the same for everyone.
      
      Please note, some drivers are doing dev->state_count = drv->state_count. This is
      not necessary because it is done by the cpuidle_enable_device function in the
      cpuidle framework. This is true, until you have the same states for all your
      devices. Otherwise, the 'low level' API should be used instead with the specific
      initialization for the driver.
      
      Let's add a wrapper function doing this initialization with a cpumask parameter
      for the coupled idle states and use it for all the drivers.
      
      That will save a lot of LOC, consolidate the code, and the modifications in the
      future could be done in a single place. Another benefit is the consolidation of
      the cpuidle_device variable which is now in the cpuidle framework and no longer
      spread accross the different arch specific drivers.
      Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
      Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
      4c637b21
  3. 03 Sep, 2012 1 commit
    • Carsten Emde's avatar
      Honor state disabling in the cpuidle ladder governor · 62d6ae88
      Carsten Emde authored
      There are two cpuidle governors ladder and menu. While the ladder
      governor is always available, if CONFIG_CPU_IDLE is selected, the
      menu governor additionally requires CONFIG_NO_HZ.
      
      A particular C state can be disabled by writing to the sysfs file
      /sys/devices/system/cpu/cpuN/cpuidle/stateN/disable, but this mechanism
      is only implemented in the menu governor. Thus, in a system where
      CONFIG_NO_HZ is not selected, the ladder governor becomes default and
      always will walk through all sleep states - irrespective of whether the
      C state was disabled via sysfs or not. The only way to select a specific
      C state was to write the related latency to /dev/cpu_dma_latency and
      keep the file open as long as this setting was required - not very
      practical and not suitable for setting a single core in an SMP system.
      
      With this patch, the ladder governor only will promote to the next
      C state, if it has not been disabled, and it will demote, if the
      current C state was disabled.
      
      Note that the patch does not make the setting of the sysfs variable
      "disable" coherent, i.e. if one is disabling a light state, then all
      deeper states are disabled as well, but the "disable" variable does not
      reflect it. Likewise, if one enables a deep state but a lighter state
      still is disabled, then this has no effect. A related section has been
      added to the documentation.
      Signed-off-by: default avatarCarsten Emde <C.Emde@osadl.org>
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      62d6ae88
  4. 30 Mar, 2012 1 commit
  5. 14 Feb, 2008 1 commit