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authorLinus Torvalds <torvalds@linux-foundation.org>2020-06-02 13:17:23 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-02 13:17:23 -0700
commit355ba37d756c38962fe9bb616f5f48eb12a7e11e (patch)
tree74bb0fc617a9a9fb5660454c205bf3d08d95896a /Documentation/power
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parenta34024d98eeaa78e2cd22017180df778800b83fc (diff)
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Merge tag 'pm-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki: "These rework the system-wide PM driver flags, make runtime switching of cpuidle governors easier, improve the user space hibernation interface code, add intel-speed-select interface documentation, add more debug messages to the ACPI code handling suspend to idle, update the cpufreq core and drivers, fix a minor issue in the cpuidle core and update two cpuidle drivers, improve the PM-runtime framework, update the Intel RAPL power capping driver, update devfreq core and drivers, and clean up the cpupower utility. Specifics: - Rework the system-wide PM driver flags to make them easier to understand and use and update their documentation (Rafael Wysocki, Alan Stern). - Allow cpuidle governors to be switched at run time regardless of the kernel configuration and update the related documentation accordingly (Hanjun Guo). - Improve the resume device handling in the user space hibernarion interface code (Domenico Andreoli). - Document the intel-speed-select sysfs interface (Srinivas Pandruvada). - Make the ACPI code handing suspend to idle print more debug messages to help diagnose issues with it (Rafael Wysocki). - Fix a helper routine in the cpufreq core and correct a typo in the struct cpufreq_driver kerneldoc comment (Rafael Wysocki, Wang Wenhu). - Update cpufreq drivers: - Make the intel_pstate driver start in the passive mode by default on systems without HWP (Rafael Wysocki). - Add i.MX7ULP support to the imx-cpufreq-dt driver and add i.MX7ULP to the cpufreq-dt-platdev blacklist (Peng Fan). - Convert the qoriq cpufreq driver to a platform one, make the platform code create a suitable device object for it and add platform dependencies to it (Mian Yousaf Kaukab, Geert Uytterhoeven). - Fix wrong compatible binding in the qcom driver (Ansuel Smith). - Build the omap driver by default for ARCH_OMAP2PLUS (Anders Roxell). - Add r8a7742 SoC support to the dt cpufreq driver (Lad Prabhakar). - Update cpuidle core and drivers: - Fix three reference count leaks in error code paths in the cpuidle core (Qiushi Wu). - Convert Qualcomm SPM to a generic cpuidle driver (Stephan Gerhold). - Fix up the execution order when entering a domain idle state in the PSCI driver (Ulf Hansson). - Fix a reference counting issue related to clock management and clean up two oddities in the PM-runtime framework (Rafael Wysocki, Andy Shevchenko). - Add ElkhartLake support to the Intel RAPL power capping driver and remove an unused local MSR definition from it (Jacob Pan, Sumeet Pawnikar). - Update devfreq core and drivers: - Replace strncpy() with strscpy() in the devfreq core and use lockdep asserts instead of manual checks for a locked mutex in it (Dmitry Osipenko, Krzysztof Kozlowski). - Add a generic imx bus scaling driver and make it register an interconnect device (Leonard Crestez, Gustavo A. R. Silva). - Make the cpufreq notifier in the tegra30 driver take boosting into account and delete an unuseful error message from that driver (Dmitry Osipenko, Markus Elfring). - Remove unneeded semicolon from the cpupower code (Zou Wei)" * tag 'pm-5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (51 commits) cpuidle: Fix three reference count leaks PM: runtime: Replace pm_runtime_callbacks_present() PM / devfreq: Use lockdep asserts instead of manual checks for locked mutex PM / devfreq: imx-bus: Fix inconsistent IS_ERR and PTR_ERR PM / devfreq: Replace strncpy with strscpy PM / devfreq: imx: Register interconnect device PM / devfreq: Add generic imx bus scaling driver PM / devfreq: tegra30: Delete an error message in tegra_devfreq_probe() PM / devfreq: tegra30: Make CPUFreq notifier to take into account boosting PM: hibernate: Restrict writes to the resume device PM: runtime: clk: Fix clk_pm_runtime_get() error path cpuidle: Convert Qualcomm SPM driver to a generic CPUidle driver ACPI: EC: PM: s2idle: Extend GPE dispatching debug message ACPI: PM: s2idle: Print type of wakeup debug messages powercap: RAPL: remove unused local MSR define PM: runtime: Make clear what we do when conditions are wrong in rpm_suspend() Documentation: admin-guide: pm: Document intel-speed-select PM: hibernate: Split off snapshot dev option PM: hibernate: Incorporate concurrency handling Documentation: ABI: make current_governer_ro as a candidate for removal ...
Diffstat (limited to 'Documentation/power')
-rw-r--r--Documentation/power/pci.rst58
1 files changed, 28 insertions, 30 deletions
diff --git a/Documentation/power/pci.rst b/Documentation/power/pci.rst
index 0924d29636ad..1831e431f725 100644
--- a/Documentation/power/pci.rst
+++ b/Documentation/power/pci.rst
@@ -1004,41 +1004,39 @@ including the PCI bus type. The flags should be set once at the driver probe
time with the help of the dev_pm_set_driver_flags() function and they should not
be updated directly afterwards.
-The DPM_FLAG_NEVER_SKIP flag prevents the PM core from using the direct-complete
-mechanism allowing device suspend/resume callbacks to be skipped if the device
-is in runtime suspend when the system suspend starts. That also affects all of
-the ancestors of the device, so this flag should only be used if absolutely
-necessary.
-
-The DPM_FLAG_SMART_PREPARE flag instructs the PCI bus type to only return a
-positive value from pci_pm_prepare() if the ->prepare callback provided by the
+The DPM_FLAG_NO_DIRECT_COMPLETE flag prevents the PM core from using the
+direct-complete mechanism allowing device suspend/resume callbacks to be skipped
+if the device is in runtime suspend when the system suspend starts. That also
+affects all of the ancestors of the device, so this flag should only be used if
+absolutely necessary.
+
+The DPM_FLAG_SMART_PREPARE flag causes the PCI bus type to return a positive
+value from pci_pm_prepare() only if the ->prepare callback provided by the
driver of the device returns a positive value. That allows the driver to opt
-out from using the direct-complete mechanism dynamically.
+out from using the direct-complete mechanism dynamically (whereas setting
+DPM_FLAG_NO_DIRECT_COMPLETE means permanent opt-out).
The DPM_FLAG_SMART_SUSPEND flag tells the PCI bus type that from the driver's
perspective the device can be safely left in runtime suspend during system
suspend. That causes pci_pm_suspend(), pci_pm_freeze() and pci_pm_poweroff()
-to skip resuming the device from runtime suspend unless there are PCI-specific
-reasons for doing that. Also, it causes pci_pm_suspend_late/noirq(),
-pci_pm_freeze_late/noirq() and pci_pm_poweroff_late/noirq() to return early
-if the device remains in runtime suspend in the beginning of the "late" phase
-of the system-wide transition under way. Moreover, if the device is in
-runtime suspend in pci_pm_resume_noirq() or pci_pm_restore_noirq(), its runtime
-power management status will be changed to "active" (as it is going to be put
-into D0 going forward), but if it is in runtime suspend in pci_pm_thaw_noirq(),
-the function will set the power.direct_complete flag for it (to make the PM core
-skip the subsequent "thaw" callbacks for it) and return.
-
-Setting the DPM_FLAG_LEAVE_SUSPENDED flag means that the driver prefers the
-device to be left in suspend after system-wide transitions to the working state.
-This flag is checked by the PM core, but the PCI bus type informs the PM core
-which devices may be left in suspend from its perspective (that happens during
-the "noirq" phase of system-wide suspend and analogous transitions) and next it
-uses the dev_pm_may_skip_resume() helper to decide whether or not to return from
-pci_pm_resume_noirq() early, as the PM core will skip the remaining resume
-callbacks for the device during the transition under way and will set its
-runtime PM status to "suspended" if dev_pm_may_skip_resume() returns "true" for
-it.
+to avoid resuming the device from runtime suspend unless there are PCI-specific
+reasons for doing that. Also, it causes pci_pm_suspend_late/noirq() and
+pci_pm_poweroff_late/noirq() to return early if the device remains in runtime
+suspend during the "late" phase of the system-wide transition under way.
+Moreover, if the device is in runtime suspend in pci_pm_resume_noirq() or
+pci_pm_restore_noirq(), its runtime PM status will be changed to "active" (as it
+is going to be put into D0 going forward).
+
+Setting the DPM_FLAG_MAY_SKIP_RESUME flag means that the driver allows its
+"noirq" and "early" resume callbacks to be skipped if the device can be left
+in suspend after a system-wide transition into the working state. This flag is
+taken into consideration by the PM core along with the power.may_skip_resume
+status bit of the device which is set by pci_pm_suspend_noirq() in certain
+situations. If the PM core determines that the driver's "noirq" and "early"
+resume callbacks should be skipped, the dev_pm_skip_resume() helper function
+will return "true" and that will cause pci_pm_resume_noirq() and
+pci_pm_resume_early() to return upfront without touching the device and
+executing the driver callbacks.
3.2. Device Runtime Power Management
------------------------------------