diff options
| author | Viresh Kumar <viresh.kumar@linaro.org> | 2017-01-06 11:08:05 +0530 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2017-02-03 23:59:40 +0100 |
| commit | 7de962c0c79a810585eb323b90561b5923614ec8 (patch) | |
| tree | 030937b36c2b2470e6db1808972cddde11d54040 /Documentation/cpu-freq/core.txt | |
| parent | 4e660759becfe91a8fb8a867a01dcb5e6f67dd26 (diff) | |
| download | lwn-7de962c0c79a810585eb323b90561b5923614ec8.tar.gz lwn-7de962c0c79a810585eb323b90561b5923614ec8.zip | |
cpufreq: Documentation: Updates based on current code
The cpufreq core has gone though lots of updates in recent times, but on
many occasions the documentation wasn't updated along with the code.
This patch tries to catchup the documentation with the code.
Also add Rafael and Viresh as the contributors to the documentation.
Based on a patch from Claudio Scordino.
Signed-off-by: Claudio Scordino <claudio@evidence.eu.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation/cpu-freq/core.txt')
| -rw-r--r-- | Documentation/cpu-freq/core.txt | 24 |
1 files changed, 13 insertions, 11 deletions
diff --git a/Documentation/cpu-freq/core.txt b/Documentation/cpu-freq/core.txt index 4bc7287806de..978463a7c81e 100644 --- a/Documentation/cpu-freq/core.txt +++ b/Documentation/cpu-freq/core.txt @@ -8,6 +8,8 @@ Dominik Brodowski <linux@brodo.de> David Kimdon <dwhedon@debian.org> + Rafael J. Wysocki <rafael.j.wysocki@intel.com> + Viresh Kumar <viresh.kumar@linaro.org> @@ -36,10 +38,11 @@ speed limits (like LCD drivers on ARM architecture). Additionally, the kernel "constant" loops_per_jiffy is updated on frequency changes here. -Reference counting is done by cpufreq_get_cpu and cpufreq_put_cpu, -which make sure that the cpufreq processor driver is correctly -registered with the core, and will not be unloaded until -cpufreq_put_cpu is called. +Reference counting of the cpufreq policies is done by cpufreq_cpu_get +and cpufreq_cpu_put, which make sure that the cpufreq driver is +correctly registered with the core, and will not be unloaded until +cpufreq_put_cpu is called. That also ensures that the respective cpufreq +policy doesn't get freed while being used. 2. CPUFreq notifiers ==================== @@ -69,18 +72,16 @@ CPUFreq policy notifier is called twice for a policy transition: The phase is specified in the second argument to the notifier. The third argument, a void *pointer, points to a struct cpufreq_policy -consisting of five values: cpu, min, max, policy and max_cpu_freq. min -and max are the lower and upper frequencies (in kHz) of the new -policy, policy the new policy, cpu the number of the affected CPU; and -max_cpu_freq the maximum supported CPU frequency. This value is given -for informational purposes only. +consisting of several values, including min, max (the lower and upper +frequencies (in kHz) of the new policy). 2.2 CPUFreq transition notifiers -------------------------------- -These are notified twice when the CPUfreq driver switches the CPU core -frequency and this change has any external implications. +These are notified twice for each online CPU in the policy, when the +CPUfreq driver switches the CPU core frequency and this change has no +any external implications. The second argument specifies the phase - CPUFREQ_PRECHANGE or CPUFREQ_POSTCHANGE. @@ -90,6 +91,7 @@ values: cpu - number of the affected CPU old - old frequency new - new frequency +flags - flags of the cpufreq driver 3. CPUFreq Table Generation with Operating Performance Point (OPP) ================================================================== |