From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: [PATCH 8/9] PM: Add facility for advanced testing of async suspend/resume Date: Thu, 10 Sep 2009 01:40:08 +0200 Message-ID: <200909100140.08687.rjw@sisk.pl> References: <200909100127.11252.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200909100127.11252.rjw@sisk.pl> Sender: linux-pci-owner@vger.kernel.org To: linux-pm Cc: LKML , Linux PCI , ACPI Devel Maling List , Len Brown , Zhang Rui , Pavel Machek , Alan Stern , Arjan van de Ven , Ingo Molnar List-Id: linux-acpi@vger.kernel.org From: Rafael J. Wysocki Add configuration switch CONFIG_PM_ADVANCED_DEBUG for compiling in extra PM debugging/testing code allowing one to access some PM-related attributes of devices from the user space via sysfs. If CONFIG_PM_ADVANCED_DEBUG is set, add sysfs attribute power/async for every device allowing the user space to access the device's power.async_suspend flag and modify it, if desired. Signed-off-by: Rafael J. Wysocki --- drivers/base/power/sysfs.c | 47 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/device.h | 5 ++++ kernel/power/Kconfig | 14 +++++++++++++ 3 files changed, 66 insertions(+) Index: linux-2.6/drivers/base/power/sysfs.c =================================================================== --- linux-2.6.orig/drivers/base/power/sysfs.c +++ linux-2.6/drivers/base/power/sysfs.c @@ -38,6 +38,22 @@ * wakeup events internally (unless they are disabled), keeping * their hardware in low power modes whenever they're unused. This * saves runtime power, without requiring system-wide sleep states. + * + * async - Report/change current async suspend setting for the device + * + * If set, the PM core will attempt to suspend and resume the device during + * system power transitions (e.g. suspend to RAM, hibernation) in parallel + * with other devices it doesn't appear to depend on (to the PM core's + * knowledge). + * + * + "enabled\n" to permit the asynchronous suspend/resume of the device + * + "disabled\n" to forbid it + * + * NOTE: It generally is unsafe to permit the asynchronous suspend/resume + * of a device unless it is certain that all of the PM dependencies of the + * device are known to the PM core. However, for some devices this + * attribute is set to "enabled" by the kernel and in that cases it should + * be safe to leave the default value. */ static const char enabled[] = "enabled"; @@ -77,9 +93,40 @@ wake_store(struct device * dev, struct d static DEVICE_ATTR(wakeup, 0644, wake_show, wake_store); +#ifdef CONFIG_PM_SLEEP_ADVANCED_DEBUG +static ssize_t async_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + return sprintf(buf, "%s\n", + device_async_suspend_enabled(dev) ? enabled : disabled); +} + +static ssize_t async_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t n) +{ + char *cp; + int len = n; + + cp = memchr(buf, '\n', n); + if (cp) + len = cp - buf; + if (len == sizeof enabled - 1 && strncmp(buf, enabled, len) == 0) + device_enable_async_suspend(dev, true); + else if (len == sizeof disabled - 1 && strncmp(buf, disabled, len) == 0) + device_enable_async_suspend(dev, false); + else + return -EINVAL; + return n; +} + +static DEVICE_ATTR(async, 0644, async_show, async_store); +#endif /* CONFIG_PM_SLEEP_ADVANCED_DEBUG */ static struct attribute * power_attrs[] = { &dev_attr_wakeup.attr, +#ifdef CONFIG_PM_SLEEP_ADVANCED_DEBUG + &dev_attr_async.attr, +#endif NULL, }; static struct attribute_group pm_attr_group = { Index: linux-2.6/include/linux/device.h =================================================================== --- linux-2.6.orig/include/linux/device.h +++ linux-2.6/include/linux/device.h @@ -478,6 +478,11 @@ static inline void device_enable_async_s dev->power.async_suspend = enable; } +static inline bool device_async_suspend_enabled(struct device *dev) +{ + return !!dev->power.async_suspend; +} + void driver_init(void); /* Index: linux-2.6/kernel/power/Kconfig =================================================================== --- linux-2.6.orig/kernel/power/Kconfig +++ linux-2.6/kernel/power/Kconfig @@ -27,6 +27,15 @@ config PM_DEBUG code. This is helpful when debugging and reporting PM bugs, like suspend support. +config PM_ADVANCED_DEBUG + bool "Extra PM attributes in sysfs for low-level debugging/testing" + depends on PM_DEBUG + default n + ---help--- + Add extra sysfs attributes allowing one to access some Power Management + fields of device objects from user space. If you are not a kernel + developer interested in debugging/testing Power Management, say "no". + config PM_VERBOSE bool "Verbose Power Management debugging" depends on PM_DEBUG @@ -85,6 +94,11 @@ config PM_SLEEP depends on SUSPEND || HIBERNATION || XEN_SAVE_RESTORE default y +config PM_SLEEP_ADVANCED_DEBUG + bool + depends on PM_ADVANCED_DEBUG + default n + config SUSPEND bool "Suspend to RAM and standby" depends on PM && ARCH_SUSPEND_POSSIBLE