From: Rafael J. Wysocki Date: Tue, 7 Dec 2021 18:54:32 +0000 (+0100) Subject: PM: runtime: Capture device status before disabling runtime PM X-Git-Tag: v6.1-rc5~2303^2~1^3~1^2~3 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c24efa6732788f0be22cdf5d2aedd5e3117e983f;p=platform%2Fkernel%2Flinux-starfive.git PM: runtime: Capture device status before disabling runtime PM In some cases (for example, during system-wide suspend and resume of devices) it is useful to know whether or not runtime PM has ever been enabled for a given device and, if so, what the runtime PM status of it had been right before runtime PM was disabled for it last time. For this reason, introduce a new struct dev_pm_info field called last_status that will be used for capturing the runtime PM status of the device when its power.disable_depth counter changes from 0 to 1. The new field will be set to RPM_INVALID to start with and whenever power.disable_depth changes from 1 to 0, so it will be valid only when runtime PM of the device is currently disabled, but it has been enabled at least once. Immediately use power.last_status in rpm_resume() to make it handle the case when PM runtime is disabled for the device, but its runtime PM status is RPM_ACTIVE more consistently. Namely, make it return 1 if power.last_status is also equal to RPM_ACTIVE in that case (the idea being that if the status was RPM_ACTIVE last time when power.disable_depth was changing from 0 to 1 and it is still RPM_ACTIVE, it can be assumed to reflect what happened to the device last time when it was using runtime PM) and -EACCES otherwise. Update the documentation to provide a description of last_status and change the description of pm_runtime_resume() in it to reflect the new behavior of rpm_active(). While at it, rearrange the code in pm_runtime_enable() to be more straightforward and replace the WARN() macro in it with a pr_warn() invocation which is less disruptive. Link: https://lore.kernel.org/linux-pm/20211026222626.39222-1-ulf.hansson@linaro.org/t/#u Reviewed-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki --- diff --git a/Documentation/power/runtime_pm.rst b/Documentation/power/runtime_pm.rst index d6bf84f..65b86e4 100644 --- a/Documentation/power/runtime_pm.rst +++ b/Documentation/power/runtime_pm.rst @@ -265,6 +265,10 @@ defined in include/linux/pm.h: RPM_SUSPENDED, which means that each device is initially regarded by the PM core as 'suspended', regardless of its real hardware status + `enum rpm_status last_status;` + - the last runtime PM status of the device captured before disabling runtime + PM for it (invalid initially and when disable_depth is 0) + `unsigned int runtime_auto;` - if set, indicates that the user space has allowed the device driver to power manage the device at run time via the /sys/devices/.../power/control @@ -333,10 +337,12 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h: `int pm_runtime_resume(struct device *dev);` - execute the subsystem-level resume callback for the device; returns 0 on - success, 1 if the device's runtime PM status was already 'active' or - error code on failure, where -EAGAIN means it may be safe to attempt to - resume the device again in future, but 'power.runtime_error' should be - checked additionally, and -EACCES means that 'power.disable_depth' is + success, 1 if the device's runtime PM status is already 'active' (also if + 'power.disable_depth' is nonzero, but the status was 'active' when it was + changing from 0 to 1) or error code on failure, where -EAGAIN means it may + be safe to attempt to resume the device again in future, but + 'power.runtime_error' should be checked additionally, and -EACCES means + that the callback could not be run, because 'power.disable_depth' was different from 0 `int pm_runtime_resume_and_get(struct device *dev);` diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c index d504cd4..844b6b8 100644 --- a/drivers/base/power/runtime.c +++ b/drivers/base/power/runtime.c @@ -742,13 +742,15 @@ static int rpm_resume(struct device *dev, int rpmflags) trace_rpm_resume_rcuidle(dev, rpmflags); repeat: - if (dev->power.runtime_error) + if (dev->power.runtime_error) { retval = -EINVAL; - else if (dev->power.disable_depth == 1 && dev->power.is_suspended - && dev->power.runtime_status == RPM_ACTIVE) - retval = 1; - else if (dev->power.disable_depth > 0) - retval = -EACCES; + } else if (dev->power.disable_depth > 0) { + if (dev->power.runtime_status == RPM_ACTIVE && + dev->power.last_status == RPM_ACTIVE) + retval = 1; + else + retval = -EACCES; + } if (retval) goto out; @@ -1410,8 +1412,10 @@ void __pm_runtime_disable(struct device *dev, bool check_resume) /* Update time accounting before disabling PM-runtime. */ update_pm_runtime_accounting(dev); - if (!dev->power.disable_depth++) + if (!dev->power.disable_depth++) { __pm_runtime_barrier(dev); + dev->power.last_status = dev->power.runtime_status; + } out: spin_unlock_irq(&dev->power.lock); @@ -1428,23 +1432,23 @@ void pm_runtime_enable(struct device *dev) spin_lock_irqsave(&dev->power.lock, flags); - if (dev->power.disable_depth > 0) { - dev->power.disable_depth--; - - /* About to enable runtime pm, set accounting_timestamp to now */ - if (!dev->power.disable_depth) - dev->power.accounting_timestamp = ktime_get_mono_fast_ns(); - } else { + if (!dev->power.disable_depth) { dev_warn(dev, "Unbalanced %s!\n", __func__); + goto out; } - WARN(!dev->power.disable_depth && - dev->power.runtime_status == RPM_SUSPENDED && - !dev->power.ignore_children && - atomic_read(&dev->power.child_count) > 0, - "Enabling runtime PM for inactive device (%s) with active children\n", - dev_name(dev)); + if (--dev->power.disable_depth > 0) + goto out; + dev->power.last_status = RPM_INVALID; + dev->power.accounting_timestamp = ktime_get_mono_fast_ns(); + + if (dev->power.runtime_status == RPM_SUSPENDED && + !dev->power.ignore_children && + atomic_read(&dev->power.child_count) > 0) + dev_warn(dev, "Enabling runtime PM for inactive device with active children\n"); + +out: spin_unlock_irqrestore(&dev->power.lock, flags); } EXPORT_SYMBOL_GPL(pm_runtime_enable); @@ -1640,6 +1644,7 @@ EXPORT_SYMBOL_GPL(__pm_runtime_use_autosuspend); void pm_runtime_init(struct device *dev) { dev->power.runtime_status = RPM_SUSPENDED; + dev->power.last_status = RPM_INVALID; dev->power.idle_notification = false; dev->power.disable_depth = 1; diff --git a/include/linux/pm.h b/include/linux/pm.h index fc9691c..e1e9402 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -521,6 +521,7 @@ const struct dev_pm_ops __maybe_unused name = { \ */ enum rpm_status { + RPM_INVALID = -1, RPM_ACTIVE = 0, RPM_RESUMING, RPM_SUSPENDED, @@ -634,6 +635,7 @@ struct dev_pm_info { unsigned int links_count; enum rpm_request request; enum rpm_status runtime_status; + enum rpm_status last_status; int runtime_error; int autosuspend_delay; u64 last_busy;