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authorSrinivas Pandruvada <srinivas.pandruvada@linux.intel.com>2023-01-17 21:22:40 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2023-01-20 20:28:19 +0300
commitc7cd6f04c0dfb6d44337f92b4c32126d20339873 (patch)
tree42064d7fc9783e2cc0ac4864dea7e308d258abd9 /drivers/powercap
parent7adc6885259edd4ef5c9a7a62fd4270cf38fdbfb (diff)
downloadlinux-c7cd6f04c0dfb6d44337f92b4c32126d20339873.tar.xz
powercap: idle_inject: Support 100% idle injection
The users of the idle injection framework allow 100% idle injection. For example: thermal/cpuidle_cooling.c driver. When the ratio is set to 100%, the runtime_duration becomes zero. However, idle_inject_set_duration() in the idle injection framework silently ignores run_duration_us == 0 without any error (it is a void function). The caller will then assume that everything is fine and 100% idle is effective, but in reality the idle duration will not change. There are two options: - The caller may change their max state to 99% instead of 100% and document that 100% is not supported by the idle inject framework. - Add 100% idle support to the idle inject framework. Since there are other protections via RT throttling, this framework can allow 100% idle. The RT throttling will be activated at 95% idle by default. The caller disabling RT throttling and injecting 100% idle, should be aware that CPU can't be used at all. The idle inject timer is started for (run_duration_us + idle_duration_us) duration. Hence replace (run_duration_us && idle_duration_us) with (run_duration_us + idle_duration_us) in the function idle_inject_set_duration(). Also check for !(run_duration_us + idle_duration_us) to return -EINVAL in idle_inject_start(). Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org> [ rjw: Changelog edits ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/powercap')
-rw-r--r--drivers/powercap/idle_inject.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
index fe86a09e3b67..c03b5402c03b 100644
--- a/drivers/powercap/idle_inject.c
+++ b/drivers/powercap/idle_inject.c
@@ -155,10 +155,12 @@ void idle_inject_set_duration(struct idle_inject_device *ii_dev,
unsigned int run_duration_us,
unsigned int idle_duration_us)
{
- if (run_duration_us && idle_duration_us) {
+ if (run_duration_us + idle_duration_us) {
WRITE_ONCE(ii_dev->run_duration_us, run_duration_us);
WRITE_ONCE(ii_dev->idle_duration_us, idle_duration_us);
}
+ if (!run_duration_us)
+ pr_debug("CPU is forced to 100 percent idle\n");
}
/**
@@ -201,7 +203,7 @@ int idle_inject_start(struct idle_inject_device *ii_dev)
unsigned int idle_duration_us = READ_ONCE(ii_dev->idle_duration_us);
unsigned int run_duration_us = READ_ONCE(ii_dev->run_duration_us);
- if (!idle_duration_us || !run_duration_us)
+ if (!(idle_duration_us + run_duration_us))
return -EINVAL;
pr_debug("Starting injecting idle cycles on CPUs '%*pbl'\n",