From c7cd6f04c0dfb6d44337f92b4c32126d20339873 Mon Sep 17 00:00:00 2001
From: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Date: Tue, 17 Jan 2023 10:22:40 -0800
Subject: [PATCH] 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>
---
drivers/powercap/idle_inject.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/powercap/idle_inject.c b/drivers/powercap/idle_inject.c
index fe86a09e3b67f..c03b5402c03b3 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",
--
2.30.2