diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-power | 29 | ||||
| -rw-r--r-- | Documentation/power/s2ram.txt | 7 | ||||
| -rw-r--r-- | drivers/base/power/trace.c | 31 | ||||
| -rw-r--r-- | include/linux/resume-trace.h | 2 | ||||
| -rw-r--r-- | kernel/power/main.c | 18 |
5 files changed, 87 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-power b/Documentation/ABI/testing/sysfs-power index 2875f1f74a0..194ca446ac2 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 514b94fc931..1bdfa044377 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 17e24e3f442..9f4258df4cf 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 bc8c3881c72..f31db236878 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 6b12a0cf4d9..7b5db6a8561 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, |