kernel/linux.git/drivers/base/power/opp/cpu.c, branch v4.14.78

PM / OPP: Move away from RCU locking

2017-01-30T08:22:22+00:00

The RCU locking isn't well suited for the OPP core. The RCU locking fits better for reader heavy stuff, while the OPP core have at max one or two readers only at a time. Over that, it was getting very confusing the way RCU locking was used with the OPP core. The individual OPPs are mostly well handled, i.e. for an update a new structure was created and then that replaced the older one. But the OPP tables were updated directly all the time from various parts of the core. Though they were mostly used from within RCU locked region, they didn't had much to do with RCU and were governed by the mutex instead. And that mixed with the 'opp_table_lock' has made the core even more confusing. Now that we are already managing the OPPs and the OPP tables with kernel reference infrastructure, we can get rid of RCU locking completely and simplify the code a lot. Remove all RCU references from code and comments. Acquire opp_table->lock while parsing the list of OPPs though. Signed-off-by: Viresh Kumar Reviewed-by: Stephen Boyd Signed-off-by: Rafael J. Wysocki

PM / OPP: Take kref from _find_opp_table()

2017-01-30T08:22:22+00:00

Take reference of the OPP table from within _find_opp_table(). Also update the callers of _find_opp_table() to call dev_pm_opp_put_opp_table() after they have used the OPP table. Note that _find_opp_table() increments the reference under the opp_table_lock. Now that the OPP table wouldn't get freed until the callers of _find_opp_table() call dev_pm_opp_put_opp_table(), there is no need to take the opp_table_lock or rcu_read_lock() around it. Drop them. Signed-off-by: Viresh Kumar Reviewed-by: Stephen Boyd Signed-off-by: Rafael J. Wysocki

PM / OPP: Update OPP users to put reference

2017-01-30T08:22:21+00:00

This patch updates dev_pm_opp_find_freq_*() routines to get a reference to the OPPs returned by them. Also updates the users of dev_pm_opp_find_freq_*() routines to call dev_pm_opp_put() after they are done using the OPPs. As it is guaranteed the that OPPs wouldn't get freed while being used, the RCU read side locking present with the users isn't required anymore. Drop it as well. This patch also updates all users of devfreq_recommended_opp() which was returning an OPP received from the OPP core. Note that some of the OPP core routines have gained rcu_read_{lock|unlock}() calls, as those still use RCU specific APIs within them. Signed-off-by: Viresh Kumar Reviewed-by: Chanwoo Choi [Devfreq] Signed-off-by: Rafael J. Wysocki

PM / OPP: Add 'UNKNOWN' status for shared_opp in struct opp_table

2016-06-16T13:50:36+00:00

dev_pm_opp_get_sharing_cpus() returns 0 even in the case when the OPP core doesn't know whether or not the table is shared. It works on the majority of platforms, where the OPP table is never created before invoking the function and then -ENODEV is returned by it. But in the case of one platform (Jetson TK1) at least, the situation is a bit different. The OPP table has been created (somehow) before dev_pm_opp_get_sharing_cpus() is called and it returns 0. Its caller treats that as 'the CPUs don't share OPPs' and that leads to degraded performance. Fix this by converting 'shared_opp' in struct opp_table to an enum and making dev_pm_opp_get_sharing_cpus() return -EINVAL in case when the value of that field is "access unknown", so that the caller can handle it accordingly (cpufreq-dt considers that as 'all CPUs share the table', for example). Fixes: 6f707daa3833 "PM / OPP: Add dev_pm_opp_get_sharing_cpus()" Reported-and-tested-by: Alexandre Courbot Signed-off-by: Viresh Kumar [ rjw : Subject & changelog ] Signed-off-by: Rafael J. Wysocki

PM / OPP: Move CONFIG_OF dependent code in a separate file

2016-05-06T11:22:49+00:00

Recently, a few issues were noticed in the code where CONFIG_OF wasn't consistently used for many routines. The core file is big enough now and ifdef hackery makes it less readable. Move OF-specific code to another file and compile that only if CONFIG_OF is enabled. Compile-tested: - For ARM (exynos) with CONFIG_OF enabled - For X86 with CONFIG_OF disabled (have to enable CONFIG_PM_OPP separately) No functional changes. Signed-off-by: Viresh Kumar Tested-by: Sudeep Holla Signed-off-by: Rafael J. Wysocki

PM / OPP: add non-OF versions of dev_pm_opp_{cpumask_, }remove_table

2016-05-04T23:38:44+00:00

Functions dev_pm_opp_of_{cpumask_,}remove_table removes/frees all the static OPP entries associated with the device and/or all cpus(in case of cpumask) that are created from DT. However the OPP entries are populated reading from the firmware or some different method using dev_pm_opp_add are marked dynamic and can't be removed using above functions. This patch adds non DT/OF versions of dev_pm_opp_{cpumask_,}remove_table to support the above mentioned usecase. This is in preparation to make use of the same in scpi-cpufreq.c Signed-off-by: Sudeep Holla Acked-by: Viresh Kumar Reviewed-by: Stephen Boyd Signed-off-by: Rafael J. Wysocki

PM / OPP: pass cpumask by reference

2016-05-04T23:34:20+00:00

The new use of dev_pm_opp_set_sharing_cpus resulted in a harmless compiler warning with CONFIG_CPUMASK_OFFSTACK=y: drivers/cpufreq/mvebu-cpufreq.c: In function 'armada_xp_pmsu_cpufreq_init': include/linux/cpumask.h:550:25: error: passing argument 2 of 'dev_pm_opp_set_sharing_cpus' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers] The problem here is that cpumask_var_t gets passed by reference, but by declaring a 'const cpumask_var_t' argument, only the pointer is constant, not the actual mask. This is harmless because the function does not actually modify the mask. This patch changes the function prototypes for all of the related functions to pass a 'struct cpumask *' instead of 'cpumask_var_t', matching what most other such functions do in the kernel. This lets us mark all the other similar functions as taking a 'const' mask where possible, and it avoids the warning without any change in object code. Signed-off-by: Arnd Bergmann Fixes: 947bd567f7a5 (mvebu: Use dev_pm_opp_set_sharing_cpus() to mark OPP tables as shared) Acked-by: Pavel Machek Acked-by: Viresh Kumar Reviewed-by: Stephen Boyd Signed-off-by: Rafael J. Wysocki

PM / OPP: Add dev_pm_opp_get_sharing_cpus()

2016-04-28T13:18:18+00:00

OPP core allows a platform to mark OPP table as shared, when the platform isn't using operating-points-v2 bindings. And, so there should be a non DT way of finding out if the OPP table is shared or not. This patch adds dev_pm_opp_get_sharing_cpus(), which first tries to get OPP sharing information from the opp-table (in case it is already marked as shared), otherwise it uses the existing DT way of finding sharing information. Signed-off-by: Viresh Kumar Acked-by: Arnd Bergmann Signed-off-by: Rafael J. Wysocki

PM / OPP: Mark cpumask as const in dev_pm_opp_set_sharing_cpus()

2016-04-28T13:18:18+00:00

dev_pm_opp_set_sharing_cpus() isn't supposed to update the cpumask passed as its parameter, and so it should always have been marked 'const'. Do it now. Signed-off-by: Viresh Kumar Acked-by: Arnd Bergmann Signed-off-by: Rafael J. Wysocki

PM / OPP: Mark shared-opp for non-dt case

2016-04-25T14:10:18+00:00

opp core allows OPPs to be explicitly marked as shared from platform code, in case of operating-point v1 bindings. Though we do everything fine in that case, we don't set the flag in the opp-table to indicate that the OPPs are shared. It works fine today as the flag isn't used anywhere else in the core, but we should be doing the right thing by marking it set. Signed-off-by: Viresh Kumar Reviewed-by: Stephen Boyd Signed-off-by: Rafael J. Wysocki