Merge tag 'pm-6.18-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull more power management updates from Rafael Wysocki:
 "These are cpufreq fixes and cleanups on top of the material merged
  previously, a power management core code fix and updates of the
  runtime PM framework including unit tests, documentation updates and
  introduction of auto-cleanup macros for runtime PM "resume and get"
  and "get without resuming" operations.

  Specifics:

   - Make cpufreq drivers setting the default CPU transition latency to
     CPUFREQ_ETERNAL specify a proper default transition latency value
     instead which addresses a regression introduced during the 6.6
     cycle that broke CPUFREQ_ETERNAL handling (Rafael Wysocki)

   - Make the cpufreq CPPC driver use a proper transition delay value
     when CPUFREQ_ETERNAL is returned by cppc_get_transition_latency()
     to indicate an error condition (Rafael Wysocki)

   - Make cppc_get_transition_latency() return a negative error code to
     indicate error conditions instead of using CPUFREQ_ETERNAL for this
     purpose and drop CPUFREQ_ETERNAL that has no other users (Rafael
     Wysocki, Gopi Krishna Menon)

   - Fix device leak in the mediatek cpufreq driver (Johan Hovold)

   - Set target frequency on all CPUs sharing a policy during frequency
     updates in the tegra186 cpufreq driver and make it initialize all
     cores to max frequencies (Aaron Kling)

   - Rust cpufreq helper cleanup (Thorsten Blum)

   - Make pm_runtime_put*() family of functions return 1 when the given
     device is already suspended which is consistent with the
     documentation (Brian Norris)

   - Add basic kunit tests for runtime PM API contracts and update
     return values in kerneldoc comments for the runtime PM API (Brian
     Norris, Dan Carpenter)

   - Add auto-cleanup macros for runtime PM "resume and get" and "get
     without resume" operations, use one of them in the PCI core and
     drop the existing "free" macro introduced for similar purpose, but
     somewhat cumbersome to use (Rafael Wysocki)

   - Make the core power management code avoid waiting on device links
     marked as SYNC_STATE_ONLY which is consistent with the handling of
     those device links elsewhere (Pin-yen Lin)"

* tag 'pm-6.18-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  docs/zh_CN: Fix malformed table
  docs/zh_TW: Fix malformed table
  PM: runtime: Fix error checking for kunit_device_register()
  PM: runtime: Introduce one more usage counter guard
  cpufreq: Drop unused symbol CPUFREQ_ETERNAL
  ACPI: CPPC: Do not use CPUFREQ_ETERNAL as an error value
  cpufreq: CPPC: Avoid using CPUFREQ_ETERNAL as transition delay
  cpufreq: Make drivers using CPUFREQ_ETERNAL specify transition latency
  PM: runtime: Drop DEFINE_FREE() for pm_runtime_put()
  PCI/sysfs: Use runtime PM guard macro for auto-cleanup
  PM: runtime: Add auto-cleanup macros for "resume and get" operations
  cpufreq: tegra186: Initialize all cores to max frequencies
  cpufreq: tegra186: Set target frequency for all cpus in policy
  rust: cpufreq: streamline find_supply_names
  cpufreq: mediatek: fix device leak on probe failure
  PM: sleep: Do not wait on SYNC_STATE_ONLY device links
  PM: runtime: Update kerneldoc return codes
  PM: runtime: Make put{,_sync}() return 1 when already suspended
  PM: runtime: Add basic kunit tests for API contracts

7 files changed, 271 insertions, 3 deletions

diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
index 064eb52ff7e2..1786d87b29e2 100644
--- a/drivers/base/Kconfig
+++ b/drivers/base/Kconfig
@@ -167,6 +167,12 @@ config PM_QOS_KUNIT_TEST
 	depends on KUNIT=y
 	default KUNIT_ALL_TESTS
 
+config PM_RUNTIME_KUNIT_TEST
+	tristate "KUnit Tests for runtime PM" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	depends on PM
+	default KUNIT_ALL_TESTS
+
 config HMEM_REPORTING
 	bool
 	default n
diff --git a/drivers/base/base.h b/drivers/base/base.h
index 700aecd22fd3..86fa7fbb3548 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -248,6 +248,7 @@ void device_links_driver_cleanup(struct device *dev);
 void device_links_no_driver(struct device *dev);
 bool device_links_busy(struct device *dev);
 void device_links_unbind_consumers(struct device *dev);
+bool device_link_flag_is_sync_state_only(u32 flags);
 void fw_devlink_drivers_done(void);
 void fw_devlink_probing_done(void);
 
diff --git a/drivers/base/core.c b/drivers/base/core.c
index fa8093119602..3c533dab8fa5 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -287,7 +287,7 @@ static bool device_is_ancestor(struct device *dev, struct device *target)
 #define DL_MARKER_FLAGS		(DL_FLAG_INFERRED | \
 				 DL_FLAG_CYCLE | \
 				 DL_FLAG_MANAGED)
-static inline bool device_link_flag_is_sync_state_only(u32 flags)
+bool device_link_flag_is_sync_state_only(u32 flags)
 {
 	return (flags & ~DL_MARKER_FLAGS) == DL_FLAG_SYNC_STATE_ONLY;
 }
diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 01f11629d241..2989e42d0161 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -4,5 +4,6 @@ obj-$(CONFIG_PM_SLEEP)	+= main.o wakeup.o wakeup_stats.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
 obj-$(CONFIG_HAVE_CLK)	+= clock_ops.o
 obj-$(CONFIG_PM_QOS_KUNIT_TEST) += qos-test.o
+obj-$(CONFIG_PM_RUNTIME_KUNIT_TEST) += runtime-test.o
 
 ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index b9a34c3425ec..e83503bdc1fd 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -278,7 +278,8 @@ static void dpm_wait_for_suppliers(struct device *dev, bool async)
 	 * walking.
 	 */
 	dev_for_each_link_to_supplier(link, dev)
-		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT &&
+		    !device_link_flag_is_sync_state_only(link->flags))
 			dpm_wait(link->supplier, async);
 
 	device_links_read_unlock(idx);
@@ -335,7 +336,8 @@ static void dpm_wait_for_consumers(struct device *dev, bool async)
 	 * unregistration).
 	 */
 	dev_for_each_link_to_consumer(link, dev)
-		if (READ_ONCE(link->status) != DL_STATE_DORMANT)
+		if (READ_ONCE(link->status) != DL_STATE_DORMANT &&
+		    !device_link_flag_is_sync_state_only(link->flags))
 			dpm_wait(link->consumer, async);
 
 	device_links_read_unlock(idx);
diff --git a/drivers/base/power/runtime-test.c b/drivers/base/power/runtime-test.c
new file mode 100644
index 000000000000..477feca804c7
--- /dev/null
+++ b/drivers/base/power/runtime-test.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2025 Google, Inc.
+ */
+
+#include <linux/cleanup.h>
+#include <linux/pm_runtime.h>
+#include <kunit/device.h>
+#include <kunit/test.h>
+
+#define DEVICE_NAME "pm_runtime_test_device"
+
+static void pm_runtime_depth_test(struct kunit *test)
+{
+	struct device *dev = kunit_device_register(test, DEVICE_NAME);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	pm_runtime_enable(dev);
+
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_get_sync(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_get_sync(dev)); /* "already active" */
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_put_sync(dev));
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_put_sync(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+}
+
+/* Test pm_runtime_put() and friends when already suspended. */
+static void pm_runtime_already_suspended_test(struct kunit *test)
+{
+	struct device *dev = kunit_device_register(test, DEVICE_NAME);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	pm_runtime_enable(dev);
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+
+	pm_runtime_get_noresume(dev);
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_barrier(dev)); /* no wakeup needed */
+	pm_runtime_put(dev);
+
+	pm_runtime_get_noresume(dev);
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_put_sync(dev));
+
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_suspend(dev));
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_autosuspend(dev));
+	KUNIT_EXPECT_EQ(test, 1, pm_request_autosuspend(dev));
+
+	pm_runtime_get_noresume(dev);
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_put_sync_autosuspend(dev));
+
+	pm_runtime_get_noresume(dev);
+	pm_runtime_put_autosuspend(dev);
+
+	/* Grab 2 refcounts */
+	pm_runtime_get_noresume(dev);
+	pm_runtime_get_noresume(dev);
+	/* The first put() sees usage_count 1 */
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_put_sync_autosuspend(dev));
+	/* The second put() sees usage_count 0 but tells us "already suspended". */
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_put_sync_autosuspend(dev));
+
+	/* Should have remained suspended the whole time. */
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+}
+
+static void pm_runtime_idle_test(struct kunit *test)
+{
+	struct device *dev = kunit_device_register(test, DEVICE_NAME);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	pm_runtime_enable(dev);
+
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_get_sync(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_runtime_idle(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+	pm_runtime_put_noidle(dev);
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_idle(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_runtime_idle(dev));
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_request_idle(dev));
+}
+
+static void pm_runtime_disabled_test(struct kunit *test)
+{
+	struct device *dev = kunit_device_register(test, DEVICE_NAME);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	/* Never called pm_runtime_enable() */
+	KUNIT_EXPECT_FALSE(test, pm_runtime_enabled(dev));
+
+	/* "disabled" is treated as "active" */
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+	KUNIT_EXPECT_FALSE(test, pm_runtime_suspended(dev));
+
+	/*
+	 * Note: these "fail", but they still acquire/release refcounts, so
+	 * keep them balanced.
+	 */
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_get(dev));
+	pm_runtime_put(dev);
+
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_get_sync(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_put_sync(dev));
+
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_get(dev));
+	pm_runtime_put_autosuspend(dev);
+
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_resume_and_get(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_idle(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_request_idle(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_request_resume(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_request_autosuspend(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_suspend(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_resume(dev));
+	KUNIT_EXPECT_EQ(test, -EACCES, pm_runtime_autosuspend(dev));
+
+	/* Still disabled */
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+	KUNIT_EXPECT_FALSE(test, pm_runtime_enabled(dev));
+}
+
+static void pm_runtime_error_test(struct kunit *test)
+{
+	struct device *dev = kunit_device_register(test, DEVICE_NAME);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	pm_runtime_enable(dev);
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+
+	/* Fake a .runtime_resume() error */
+	dev->power.runtime_error = -EIO;
+
+	/*
+	 * Note: these "fail", but they still acquire/release refcounts, so
+	 * keep them balanced.
+	 */
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_get(dev));
+	pm_runtime_put(dev);
+
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_get_sync(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_put_sync(dev));
+
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_get(dev));
+	pm_runtime_put_autosuspend(dev);
+
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_get(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_put_sync_autosuspend(dev));
+
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_resume_and_get(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_idle(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_request_idle(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_request_resume(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_request_autosuspend(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_suspend(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_resume(dev));
+	KUNIT_EXPECT_EQ(test, -EINVAL, pm_runtime_autosuspend(dev));
+
+	/* Error is still pending */
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+	KUNIT_EXPECT_EQ(test, -EIO, dev->power.runtime_error);
+	/* Clear error */
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_set_suspended(dev));
+	KUNIT_EXPECT_EQ(test, 0, dev->power.runtime_error);
+	/* Still suspended */
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_get(dev));
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_barrier(dev)); /* resume was pending */
+	pm_runtime_put(dev);
+	pm_runtime_suspend(dev); /* flush the put(), to suspend */
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_get_sync(dev));
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_put_sync(dev));
+
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_get_sync(dev));
+	pm_runtime_put_autosuspend(dev);
+
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_resume_and_get(dev));
+
+	/*
+	 * The following should all return -EAGAIN (usage is non-zero) or 1
+	 * (already resumed).
+	 */
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_runtime_idle(dev));
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_request_idle(dev));
+	KUNIT_EXPECT_EQ(test, 1, pm_request_resume(dev));
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_request_autosuspend(dev));
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_runtime_suspend(dev));
+	KUNIT_EXPECT_EQ(test, 1, pm_runtime_resume(dev));
+	KUNIT_EXPECT_EQ(test, -EAGAIN, pm_runtime_autosuspend(dev));
+
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_put_sync(dev));
+
+	/* Suspended again */
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+}
+
+/*
+ * Explore a typical probe() sequence in which a device marks itself powered,
+ * but doesn't hold any runtime PM reference, so it suspends as soon as it goes
+ * idle.
+ */
+static void pm_runtime_probe_active_test(struct kunit *test)
+{
+	struct device *dev = kunit_device_register(test, DEVICE_NAME);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	KUNIT_EXPECT_TRUE(test, pm_runtime_status_suspended(dev));
+
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_set_active(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+
+	pm_runtime_enable(dev);
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+
+	/* Nothing to flush. We stay active. */
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_barrier(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_active(dev));
+
+	/* Ask for idle? Now we suspend. */
+	KUNIT_EXPECT_EQ(test, 0, pm_runtime_idle(dev));
+	KUNIT_EXPECT_TRUE(test, pm_runtime_suspended(dev));
+}
+
+static struct kunit_case pm_runtime_test_cases[] = {
+	KUNIT_CASE(pm_runtime_depth_test),
+	KUNIT_CASE(pm_runtime_already_suspended_test),
+	KUNIT_CASE(pm_runtime_idle_test),
+	KUNIT_CASE(pm_runtime_disabled_test),
+	KUNIT_CASE(pm_runtime_error_test),
+	KUNIT_CASE(pm_runtime_probe_active_test),
+	{}
+};
+
+static struct kunit_suite pm_runtime_test_suite = {
+	.name = "pm_runtime_test_cases",
+	.test_cases = pm_runtime_test_cases,
+};
+
+kunit_test_suite(pm_runtime_test_suite);
+MODULE_DESCRIPTION("Runtime power management unit test suite");
+MODULE_LICENSE("GPL");
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 7420b9851fe0..1b11a3cd4acc 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -498,6 +498,9 @@ static int rpm_idle(struct device *dev, int rpmflags)
 	if (retval < 0)
 		;	/* Conditions are wrong. */
 
+	else if ((rpmflags & RPM_GET_PUT) && retval == 1)
+		;	/* put() is allowed in RPM_SUSPENDED */
+
 	/* Idle notifications are allowed only in the RPM_ACTIVE state. */
 	else if (dev->power.runtime_status != RPM_ACTIVE)
 		retval = -EAGAIN;
@@ -796,6 +799,8 @@ static int rpm_resume(struct device *dev, int rpmflags)
 		if (dev->power.runtime_status == RPM_ACTIVE &&
 		    dev->power.last_status == RPM_ACTIVE)
 			retval = 1;
+		else if (rpmflags & RPM_TRANSPARENT)
+			goto out;
 		else
 			retval = -EACCES;
 	}