PM: Add sysfs attr for rechecking dev hash from PM trace (d33ac60b) · Commits · e / devices / android_kernel_teracube_2e

Documentation/ABI/testing/sysfs-power

+29 −0

Original line number	Original line	Diff line number	Diff line
	@@ -99,9 +99,38 @@ Description:

	dmesg -s 1000000 \| grep 'hash matches'		dmesg -s 1000000 \| grep 'hash matches'

			If you do not get any matches (or they appear to be false
			positives), it is possible that the last PM event point
			referred to a device created by a loadable kernel module. In
			this case cat /sys/power/pm_trace_dev_match (see below) after
			your system is started up and the kernel modules are loaded.

	CAUTION: Using it will cause your machine's real-time (CMOS)		CAUTION: Using it will cause your machine's real-time (CMOS)
	clock to be set to a random invalid time after a resume.		clock to be set to a random invalid time after a resume.

			What; /sys/power/pm_trace_dev_match
			Date: October 2010
			Contact: James Hogan <james@albanarts.com>
			Description:
			The /sys/power/pm_trace_dev_match file contains the name of the
			device associated with the last PM event point saved in the RTC
			across reboots when pm_trace has been used. More precisely it
			contains the list of current devices (including those
			registered by loadable kernel modules since boot) which match
			the device hash in the RTC at boot, with a newline after each
			one.

			The advantage of this file over the hash matches printed to the
			kernel log (see /sys/power/pm_trace), is that it includes
			devices created after boot by loadable kernel modules.

			Due to the small hash size necessary to fit in the RTC, it is
			possible that more than one device matches the hash, in which
			case further investigation is required to determine which
			device is causing the problem. Note that genuine RTC clock
			values (such as when pm_trace has not been used), can still
			match a device and output it's name here.

	What: /sys/power/pm_async		What: /sys/power/pm_async
	Date: January 2009		Date: January 2009
	Contact: Rafael J. Wysocki <rjw@sisk.pl>		Contact: Rafael J. Wysocki <rjw@sisk.pl>

Documentation/power/s2ram.txt

+7 −0

Original line number	Original line	Diff line number	Diff line
	@@ -49,6 +49,13 @@ machine that doesn't boot) is:
	device (lspci and /sys/devices/pci* is your friend), and see if you can		device (lspci and /sys/devices/pci* is your friend), and see if you can
	fix it, disable it, or trace into its resume function.		fix it, disable it, or trace into its resume function.

			If no device matches the hash (or any matches appear to be false positives),
			the culprit may be a device from a loadable kernel module that is not loaded
			until after the hash is checked. You can check the hash against the current
			devices again after more modules are loaded using sysfs:

			cat /sys/power/pm_trace_dev_match

	For example, the above happens to be the VGA device on my EVO, which I		For example, the above happens to be the VGA device on my EVO, which I
	used to run with "radeonfb" (it's an ATI Radeon mobility). It turns out		used to run with "radeonfb" (it's an ATI Radeon mobility). It turns out
	that "radeonfb" simply cannot resume that device - it tries to set the		that "radeonfb" simply cannot resume that device - it tries to set the

drivers/base/power/trace.c

+31 −0

Original line number	Original line	Diff line number	Diff line
	@@ -207,6 +207,37 @@ static int show_dev_hash(unsigned int value)

	static unsigned int hash_value_early_read;		static unsigned int hash_value_early_read;

			int show_trace_dev_match(char *buf, size_t size)
			{
			unsigned int value = hash_value_early_read / (USERHASH * FILEHASH);
			int ret = 0;
			struct list_head *entry;

			/*
			* It's possible that multiple devices will match the hash and we can't
			* tell which is the culprit, so it's best to output them all.
			*/
			device_pm_lock();
			entry = dpm_list.prev;
			while (size && entry != &dpm_list) {
			struct device *dev = to_device(entry);
			unsigned int hash = hash_string(DEVSEED, dev_name(dev),
			DEVHASH);
			if (hash == value) {
			int len = snprintf(buf, size, "%s\n",
			dev_driver_string(dev));
			if (len > size)
			len = size;
			buf += len;
			ret += len;
			size -= len;
			}
			entry = entry->prev;
			}
			device_pm_unlock();
			return ret;
			}

	static int early_resume_init(void)		static int early_resume_init(void)
	{		{
	hash_value_early_read = read_magic_time();		hash_value_early_read = read_magic_time();

include/linux/resume-trace.h

+2 −0

Original line number	Original line	Diff line number	Diff line
	@@ -3,6 +3,7 @@

	#ifdef CONFIG_PM_TRACE		#ifdef CONFIG_PM_TRACE
	#include <asm/resume-trace.h>		#include <asm/resume-trace.h>
			#include <linux/types.h>

	extern int pm_trace_enabled;		extern int pm_trace_enabled;

	@@ -14,6 +15,7 @@ static inline int pm_trace_is_enabled(void)
	struct device;		struct device;
	extern void set_trace_device(struct device *);		extern void set_trace_device(struct device *);
	extern void generate_resume_trace(const void *tracedata, unsigned int user);		extern void generate_resume_trace(const void *tracedata, unsigned int user);
			extern int show_trace_dev_match(char *buf, size_t size);

	#define TRACE_DEVICE(dev) do { \		#define TRACE_DEVICE(dev) do { \
	if (pm_trace_enabled) \		if (pm_trace_enabled) \

kernel/power/main.c

+18 −0

Original line number	Original line	Diff line number	Diff line
	@@ -281,12 +281,30 @@ pm_trace_store(struct kobject kobj, struct kobj_attribute attr,
	}		}

	power_attr(pm_trace);		power_attr(pm_trace);

			static ssize_t pm_trace_dev_match_show(struct kobject *kobj,
			struct kobj_attribute *attr,
			char *buf)
			{
			return show_trace_dev_match(buf, PAGE_SIZE);
			}

			static ssize_t
			pm_trace_dev_match_store(struct kobject kobj, struct kobj_attribute attr,
			const char *buf, size_t n)
			{
			return -EINVAL;
			}

			power_attr(pm_trace_dev_match);

	#endif /* CONFIG_PM_TRACE */		#endif /* CONFIG_PM_TRACE */

	static struct attribute * g[] = {		static struct attribute * g[] = {
	&state_attr.attr,		&state_attr.attr,
	#ifdef CONFIG_PM_TRACE		#ifdef CONFIG_PM_TRACE
	&pm_trace_attr.attr,		&pm_trace_attr.attr,
			&pm_trace_dev_match_attr.attr,
	#endif		#endif
	#ifdef CONFIG_PM_SLEEP		#ifdef CONFIG_PM_SLEEP
	&pm_async_attr.attr,		&pm_async_attr.attr,