kernel/linux.git/drivers/base/power/domain.c, branch linux-4.16.y

PM / domains: Fix up domain-idle-states OF parsing

2018-02-07T11:02:01+00:00

Commit b539cc82d493 (PM / Domains: Ignore domain-idle-states that are not compatible), made it possible to ignore non-compatible domain-idle-states OF nodes. However, in case that happens while doing the OF parsing, the number of elements in the allocated array would exceed the numbers actually needed, thus wasting memory. Fix this by pre-iterating the genpd OF node and counting the number of compatible domain-idle-states nodes, before doing the allocation. While doing this, it makes sense to rework the code a bit to avoid open coding, of parts responsible for the OF node iteration. Let's also take the opportunity to clarify the function header for of_genpd_parse_idle_states(), about what is being returned in case of errors. Fixes: b539cc82d493 (PM / Domains: Ignore domain-idle-states that are not compatible) Signed-off-by: Ulf Hansson Reviewed-by: Lina Iyer Signed-off-by: Rafael J. Wysocki

PM / genpd: Stop/start devices without pm_runtime_force_suspend/resume()

2018-01-15T00:33:37+00:00

There are problems with calling pm_runtime_force_suspend/resume() to "stop" and "start" devices in genpd_finish_suspend() and genpd_resume_noirq() (and in analogous hibernation-specific genpd callbacks) after commit 122a22377a3d (PM / Domains: Stop/start devices during system PM suspend/resume in genpd) as those routines do much more than just "stopping" and "starting" devices (which was the stated purpose of that commit) unnecessarily and may not play well with system-wide PM driver callbacks. First, consider the pm_runtime_force_suspend() in genpd_finish_suspend(). If the current runtime PM status of the device is "suspended", that function most likely does the right thing by ignoring the device, because it should have been "stopped" already and whatever needed to be done to deactivate it shoud have been done. In turn, if the runtime PM status of the device is "active", genpd_runtime_suspend() is called for it (indirectly) and (1) runs the ->runtime_suspend callback provided by the device's driver (assuming no bus type with ->runtime_suspend of its own), (2) "stops" the device and (3) checks if the domain can be powered down, and then (4) the device's runtime PM status is changed to "suspended". Out of the four actions above (1) is not necessary and it may be outright harmful, (3) is pointless and (4) is questionable. The only operation that needs to be carried out here is (2). The reason why (1) is not necessary is because the system-wide PM callbacks provided by the device driver for the transition in question have been run and they should have taken care of the driver's part of device suspend already. Moreover, it may be harmful, because the ->runtime_suspend callback may want to access the device which is partially suspended at that point and may not be responsive. Also, system-wide PM callbacks may have been run already (in the previous phases of the system transition under way) for the device's parent or for its supplier devices (if any) and the device may not be accessible because of that. There also is no reason to do (3), because genpd_finish_suspend() will repeat it anyway, and (4) potentially causes confusion to ensue during the subsequent system transition to the working state. Consider pm_runtime_force_resume() in genpd_resume_noirq() now. It runs genpd_runtime_resume() for all devices with runtime PM status set to "suspended", which includes all of the devices whose runtime PM status was changed by pm_runtime_force_suspend() before and may include some devices already suspended when the pm_runtime_force_suspend() was running, which may be confusing. The genpd_runtime_resume() first tries to power up the domain, which (again) is pointless, because genpd_resume_noirq() has done that already. Then, it "starts" the device and runs the ->runtime_resume callback (from the driver, say) for it. If all is well, the device is left with the runtime PM status set to "active". Unfortunately, running the driver's ->runtime_resume callback before its system-wide PM callbacks and possibly before some system-wide PM callbacks of the parent device's driver (let alone supplier drivers) is asking for trouble, especially if the device had been suspended before pm_runtime_force_suspend() ran previously or if the callbacks in question expect to be run back-to-back with their suspend-side counterparts. It also should not be necessary, because the system-wide PM driver callbacks that will be invoked for the device subsequently should take care of resuming it just fine. [Running the driver's ->runtime_resume callback in the "noirq" phase of the transition to the working state may be problematic even for devices whose drivers do use pm_runtime_force_resume() in (or as) their system-wide PM callbacks if they have suppliers other than their parents, because it may cause the supplier to be resumed after the consumer in some cases.] Because of the above, modify genpd as follows: 1. Change genpd_finish_suspend() to only "stop" devices with runtime PM status set to "active" (without invoking runtime PM callbacks for them, changing their runtime PM status and so on). That doesn't change the handling of devices whose drivers use pm_runtime_force_suspend/resume() in (or as) their system-wide PM callbacks and addresses the issues described above for the other devices. 2. Change genpd_resume_noirq() to only "start" devices with runtime PM status set to "active" (without invoking runtime PM callbacks for them, changing their runtime PM status and so on). Again, that doesn't change the handling of devices whose drivers use pm_runtime_force_suspend/resume() in (or as) their system-wide PM callbacks and addresses the described issues for the other devices. Devices with runtime PM status set to "suspended" are not started with the assumption that they will be resumed later, either by pm_runtime_force_resume() or via runtime PM. 3. Change genpd_restore_noirq() to follow genpd_resume_noirq(). That causes devices already suspended before hibernation to be left alone (which also is the case without the change) and avoids running the ->runtime_resume driver callback too early for the other devices. 4. Change genpd_freeze_noirq() and genpd_thaw_noirq() in accordance with the above modifications. Fixes: 122a22377a3d (PM / Domains: Stop/start devices during system PM suspend/resume in genpd) Signed-off-by: Rafael J. Wysocki Acked-by: Ulf Hansson

PM / domains: Don't skip driver's ->suspend|resume_noirq() callbacks

2018-01-11T00:57:44+00:00

Commit 10da65423fdb (PM / Domains: Call driver's noirq callbacks) started to respect driver's noirq callbacks, but while doing that it also introduced a few potential problems. More precisely, in genpd_finish_suspend() and genpd_resume_noirq() the noirq callbacks at the driver level should be invoked, no matter of whether dev->power.wakeup_path is set or not. Additionally, the commit in question also made genpd_resume_noirq() to ignore the return value from pm_runtime_force_resume(). Let's fix both these issues! Fixes: 10da65423fdb (PM / Domains: Call driver's noirq callbacks) Signed-off-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki

PM / Domains: Remove obsolete "samsung,power-domain" check

2017-12-13T00:34:47+00:00

Currently the generic PM Domain code code checks for the presence of both (generic) "power-domains" and (Samsung Exynos legacy) "samsung,power-domain" properties in all device tree nodes representing devices. There are two issues with this: 1. This imposes a small boot-time penalty on all platforms using DT, 2. Platform-specific checks do not really belong in core framework code. Remove the platform-specific check, as the last user of "samsung,power-domain" was removed in commit 46dcf0ff0de35da8 ("ARM: dts: exynos: Remove exynos4415.dtsi"). All other users were converted before in commit 0da6587041363033 ("ARM: dts: convert to generic power domain bindings for exynos DT"). Signed-off-by: Geert Uytterhoeven Acked-by: Ulf Hansson Acked-by: Krzysztof Kozlowski Signed-off-by: Rafael J. Wysocki

Merge branch 'pm-qos'

2017-11-13T00:33:48+00:00

* pm-qos: PM / QoS: Fix device resume latency framework PM / QoS: Drop PM_QOS_FLAG_REMOTE_WAKEUP

PM / Domains: Fix genpd to deal with drivers returning 1 from ->prepare()

2017-11-08T11:16:57+00:00

During system-wide PM, genpd relies on its PM callbacks to be invoked for all its attached devices, as to deal with powering off/on the PM domain. In other words, genpd is not compatible with the direct_complete path, if executed by the PM core for any of its attached devices. However, when genpd's ->prepare() callback invokes pm_generic_prepare(), it does not take into account that it may return 1. Instead it treats that as an error internally and expects the PM core to abort the prepare phase and roll back. This leads to genpd not properly powering on/off the PM domain, because its internal counters gets wrongly balanced. To fix the behaviour, allow drivers to return 1 from their ->prepare() callbacks, but let's return 0 from genpd's ->prepare() callback in such case, as that prevents the PM core from running the direct_complete path for the device. Signed-off-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki

PM / QoS: Fix device resume latency framework

2017-11-08T11:14:51+00:00

The special value of 0 for device resume latency PM QoS means "no restriction", but there are two problems with that. First, device resume latency PM QoS requests with 0 as the value are always put in front of requests with positive values in the priority lists used internally by the PM QoS framework, causing 0 to be chosen as an effective constraint value. However, that 0 is then interpreted as "no restriction" effectively overriding the other requests with specific restrictions which is incorrect. Second, the users of device resume latency PM QoS have no way to specify that *any* resume latency at all should be avoided, which is an artificial limitation in general. To address these issues, modify device resume latency PM QoS to use S32_MAX as the "no constraint" value and 0 as the "no latency at all" one and rework its users (the cpuidle menu governor, the genpd QoS governor and the runtime PM framework) to follow these changes. Also add a special "n/a" value to the corresponding user space I/F to allow user space to indicate that it cannot accept any resume latencies at all for the given device. Fixes: 85dc0b8a4019 (PM / QoS: Make it possible to expose PM QoS latency constraints) Link: https://bugzilla.kernel.org/show_bug.cgi?id=197323 Reported-by: Reinette Chatre Signed-off-by: Rafael J. Wysocki Tested-by: Reinette Chatre Tested-by: Geert Uytterhoeven Tested-by: Tero Kristo Reviewed-by: Ramesh Thomas

Merge branch 'pm-domains' into pm-qos

2017-11-08T11:14:38+00:00

PM / domains: Rework governor code to be more consistent

2017-11-08T11:13:13+00:00

The genpd governor currently uses negative PM QoS values to indicate the "no suspend" condition and 0 as "no restriction", but it doesn't use them consistently. Moreover, it tries to refresh QoS values for already suspended devices in a quite questionable way. For the above reasons, rework it to be a bit more consistent. First off, note that dev_pm_qos_read_value() in dev_update_qos_constraint() and __default_power_down_ok() is evaluated for devices in suspend. Moreover, that only happens if the effective_constraint_ns value for them is negative (meaning "no suspend"). It is not evaluated in any other cases, so effectively the QoS values are only updated for devices in suspend that should not have been suspended in the first place. In all of the other cases, the QoS values taken into account are the effective ones from the time before the device has been suspended, so generally devices need to be resumed and suspended again for new QoS values to take effect anyway. Thus evaluating dev_update_qos_constraint() in those two places doesn't make sense at all, so drop it. Second, initialize effective_constraint_ns to 0 ("no constraint") rather than to (-1) ("no suspend"), which makes more sense in general and in case effective_constraint_ns is never updated (the device is in suspend all the time or it is never suspended) it doesn't affect the device's parent and so on. Finally, rework default_suspend_ok() to explicitly handle the "no restriction" and "no suspend" special cases. Signed-off-by: Rafael J. Wysocki Tested-by: Geert Uytterhoeven Tested-by: Tero Kristo Reviewed-by: Ramesh Thomas

PM / Domains: Remove gpd_dev_ops.active_wakeup() callback

2017-11-08T00:00:48+00:00

There are no more users left of the gpd_dev_ops.active_wakeup() callback. All have been converted to GENPD_FLAG_ACTIVE_WAKEUP. Hence remove the callback. Signed-off-by: Geert Uytterhoeven Acked-by: Ulf Hansson Reviewed-by: Kevin Hilman Signed-off-by: Rafael J. Wysocki