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-rw-r--r--Documentation/ABI/testing/sysfs-power29
-rw-r--r--Documentation/power/s2ram.txt7
-rw-r--r--drivers/base/power/trace.c31
-rw-r--r--include/linux/resume-trace.h2
-rw-r--r--kernel/power/main.c18
5 files changed, 87 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power
index 2875f1f74a07..194ca446ac28 100644
--- a/Documentation/ABI/testing/sysfs-power
+++ b/Documentation/ABI/testing/sysfs-power
@@ -99,9 +99,38 @@ Description:
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)
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
Date: January 2009
Contact: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/Documentation/power/s2ram.txt b/Documentation/power/s2ram.txt
index 514b94fc931e..1bdfa0443773 100644
--- a/Documentation/power/s2ram.txt
+++ b/Documentation/power/s2ram.txt
@@ -49,6 +49,13 @@ machine that doesn't boot) is:
device (lspci and /sys/devices/pci* is your friend), and see if you can
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
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
diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index 17e24e3f4422..9f4258df4cfd 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -207,6 +207,37 @@ static int show_dev_hash(unsigned int value)
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)
{
hash_value_early_read = read_magic_time();
diff --git a/include/linux/resume-trace.h b/include/linux/resume-trace.h
index bc8c3881c729..f31db2368782 100644
--- a/include/linux/resume-trace.h
+++ b/include/linux/resume-trace.h
@@ -3,6 +3,7 @@
#ifdef CONFIG_PM_TRACE
#include <asm/resume-trace.h>
+#include <linux/types.h>
extern int pm_trace_enabled;
@@ -14,6 +15,7 @@ static inline int pm_trace_is_enabled(void)
struct device;
extern void set_trace_device(struct device *);
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 { \
if (pm_trace_enabled) \
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 6b12a0cf4d9f..7b5db6a8561e 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -281,12 +281,30 @@ pm_trace_store(struct kobject *kobj, struct kobj_attribute *attr,
}
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 */
static struct attribute * g[] = {
&state_attr.attr,
#ifdef CONFIG_PM_TRACE
&pm_trace_attr.attr,
+ &pm_trace_dev_match_attr.attr,
#endif
#ifdef CONFIG_PM_SLEEP
&pm_async_attr.attr,