kernel/linux.git/drivers/base/power/common.c, branch v6.19.11

PM: domains: Detach on device_unbind_cleanup()

2025-07-07T18:41:21+00:00

The dev_pm_domain_attach() function is typically used in bus code alongside dev_pm_domain_detach(), often following patterns like: static int bus_probe(struct device *_dev) { struct bus_driver *drv = to_bus_driver(dev->driver); struct bus_device *dev = to_bus_device(_dev); int ret; // ... ret = dev_pm_domain_attach(_dev, true); if (ret) return ret; if (drv->probe) ret = drv->probe(dev); // ... } static void bus_remove(struct device *_dev) { struct bus_driver *drv = to_bus_driver(dev->driver); struct bus_device *dev = to_bus_device(_dev); if (drv->remove) drv->remove(dev); dev_pm_domain_detach(_dev); } When the driver's probe function uses devres-managed resources that depend on the power domain state, those resources are released later during device_unbind_cleanup(). Releasing devres-managed resources that depend on the power domain state after detaching the device from its PM domain can cause failures. For example, if the driver uses devm_pm_runtime_enable() in its probe function, and the device's clocks are managed by the PM domain, then during removal the runtime PM is disabled in device_unbind_cleanup() after the clocks have been removed from the PM domain. It may happen that the devm_pm_runtime_enable() action causes the device to be runtime- resumed. If the driver specific runtime PM APIs access registers directly, this will lead to accessing device registers without clocks being enabled. Similar issues may occur with other devres actions that access device registers. Add detach_power_off member to struct dev_pm_info, to be used later in device_unbind_cleanup() as the power_off argument for dev_pm_domain_detach(). This is a preparatory step toward removing dev_pm_domain_detach() calls from bus remove functions. Since the current PM domain detach functions (genpd_dev_pm_detach() and acpi_dev_pm_detach()) already set dev->pm_domain = NULL, there should be no issues with bus drivers that still call dev_pm_domain_detach() in their remove functions. Signed-off-by: Claudiu Beznea Reviewed-by: Ulf Hansson Link: https://patch.msgid.link/20250703112708.1621607-3-claudiu.beznea.uj@bp.renesas.com Signed-off-by: Rafael J. Wysocki

PM: domains: Add flags to specify power on attach/detach

2025-07-07T18:41:20+00:00

Calling dev_pm_domain_attach()/dev_pm_domain_detach() in bus driver probe/remove functions can affect system behavior when the drivers attached to the bus use devres-managed resources. Since devres actions may need to access device registers, calling dev_pm_domain_detach() too early, i.e., before these actions complete, can cause failures on some systems. One such example is Renesas RZ/G3S SoC-based platforms. If the device clocks are managed via PM domains, invoking dev_pm_domain_detach() in the bus driver's remove function removes the device's clocks from the PM domain, preventing any subsequent pm_runtime_resume*() calls from enabling those clocks. The second argument of dev_pm_domain_attach() specifies whether the PM domain should be powered on during attachment. Likewise, the second argument of dev_pm_domain_detach() indicates whether the domain should be powered off during detachment. Upcoming changes address the issue described above (initially for the platform bus only) by deferring the call to dev_pm_domain_detach() until after devres_release_all() in device_unbind_cleanup(). The detach_power_off field in struct dev_pm_info stores the detach power off info from the second argument of dev_pm_domain_attach(). Because there are cases where the device's PM domain power-on/off behavior must be conditional (e.g., in i2c_device_probe()), the patch introduces PD_FLAG_ATTACH_POWER_ON and PD_FLAG_DETACH_POWER_OFF flags to be passed to dev_pm_domain_attach(). Finally, dev_pm_domain_attach() and its users are updated to use the newly introduced PD_FLAG_ATTACH_POWER_ON and PD_FLAG_DETACH_POWER_OFF macros. This change is preparatory. Signed-off-by: Claudiu Beznea Reviewed-by: Mathieu Poirier Acked-by: Wolfram Sang # I2C Reviewed-by: Ulf Hansson Link: https://patch.msgid.link/20250703112708.1621607-2-claudiu.beznea.uj@bp.renesas.com [ rjw: Changelog adjustments ] Signed-off-by: Rafael J. Wysocki

PM: domains: Support required OPPs in dev_pm_domain_attach_list()

2024-10-10T12:13:49+00:00

In the multiple PM domain case we need platform code to specify the index of the corresponding required OPP in DT for a device, which is what *_opp_attach_genpd() is there to help us with. However, attaching a device to its PM domains is in general better done with dev_pm_domain_attach_list(). To avoid having two different ways to manage this and to prepare for the removal of *_opp_attach_genpd(), let's extend dev_pm_domain_attach|detach_list() to manage the required OPPs too. Signed-off-by: Ulf Hansson Acked-by: Viresh Kumar Link: https://lore.kernel.org/r/20241002122232.194245-5-ulf.hansson@linaro.org

PM: domains: Fix alloc/free in dev_pm_domain_attach|detach_list()

2024-10-10T11:55:17+00:00

The dev_pm_domain_attach|detach_list() functions are not resource managed, hence they should not use devm_* helpers to manage allocation/freeing of data. Let's fix this by converting to the traditional alloc/free functions. Fixes: 161e16a5e50a ("PM: domains: Add helper functions to attach/detach multiple PM domains") Cc: stable@vger.kernel.org Signed-off-by: Ulf Hansson Acked-by: Viresh Kumar Link: https://lore.kernel.org/r/20241002122232.194245-3-ulf.hansson@linaro.org

PM: domains: add device managed version of dev_pm_domain_attach|detach_list()

2024-08-20T09:19:49+00:00

Add the devres-enabled version of dev_pm_domain_attach|detach_list. If client drivers use devm_pm_domain_attach_list() to attach the PM domains, devm_pm_domain_detach_list() will be invoked implicitly during remove phase. Signed-off-by: Dikshita Agarwal Link: https://lore.kernel.org/r/1724063350-11993-2-git-send-email-quic_dikshita@quicinc.com Signed-off-by: Ulf Hansson

PM: domains: Add helper functions to attach/detach multiple PM domains

2024-02-14T09:26:11+00:00

Attaching/detaching of a device to multiple PM domains has started to become a common operation for many drivers, typically during ->probe() and ->remove(). In most cases, this has lead to lots of boilerplate code in the drivers. To fixup up the situation, let's introduce a pair of helper functions, dev_pm_domain_attach|detach_list(), that driver can use instead of the open-coding. Note that, it seems reasonable to limit the support for these helpers to DT based platforms, at it's the only valid use case for now. Suggested-by: Daniel Baluta Tested-by: Bryan O'Donoghue Tested-by: Iuliana Prodan Signed-off-by: Ulf Hansson Link: https://lore.kernel.org/r/20240130123951.236243-2-ulf.hansson@linaro.org

PM: domains: Introduce dev_pm_domain_set_performance_state()

2023-10-06T07:07:33+00:00

The generic PM domain is currently the only PM domain variant that supports performance scaling. To allow performance scaling to be supported through a common interface, let's add an optional callback ->set_performance_state(), in the struct dev_pm_domain. Moreover, let's add a function, dev_pm_domain_set_performance_state(), that may be called by consumers to request a new performance state for a device through its PM domain. Note that, in most cases it's preferred that a consumer use the OPP library to request a new performance state for its device. Although, this requires some additional changes to be supported, which are being implemented from subsequent changes. Signed-off-by: Ulf Hansson Acked-by: Rafael J. Wysocki Signed-off-by: Viresh Kumar

PM: domains: Extend dev_pm_domain_detach() doc

2022-04-13T15:07:58+00:00

Mention all domain attach menthods which dev_pm_domain_detach() reverses. Signed-off-by: Krzysztof Kozlowski Signed-off-by: Rafael J. Wysocki

PM / Domains: Introduce dev_pm_domain_start()

2019-11-13T10:41:50+00:00

For a subsystem/driver that either doesn't support runtime PM or makes use of pm_runtime_set_active() during ->probe(), may try to access its device when probing, even if it may not be fully powered on from the PM domain's point of view. This may be the case when the used PM domain is a genpd provider, that implements genpd's ->start|stop() device callbacks. There are cases where the subsystem/driver managed to avoid the above problem, simply by calling pm_runtime_enable() and pm_runtime_get_sync() during ->probe(). However, this approach comes with a drawback, especially if the subsystem/driver implements a ->runtime_resume() callback. More precisely, the subsystem/driver then needs to use a device flag, which is checked in its ->runtime_resume() callback, as to avoid powering on its resources the first time the callback is invoked. This is needed because the subsystem/driver has already powered on the resources for the device, during ->probe() and before it called pm_runtime_get_sync(). In a way to avoid this boilerplate code and the inefficient check for "if (first_time_suspend)" in the ->runtime_resume() callback for these subsystems/drivers, let's introduce and export a dev_pm_domain_start() function, that may be called during ->probe() instead. Moreover, let the dev_pm_domain_start() invoke an optional ->start() callback, added to the struct dev_pm_domain, as to allow a PM domain specific implementation. Signed-off-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki

drivers: base: power: add proper SPDX identifiers on files that did not have them.

2019-04-04T18:03:40+00:00

There were a few files in the driver core power code that did not have SPDX identifiers on them, so fix that up. At the same time, remove the "free form" text that specified the license of the file, as that is impossible for any tool to properly parse. Cc: "Rafael J. Wysocki" Signed-off-by: Greg Kroah-Hartman