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    SubjectRe: [patch 2.6.26-rc4-git] PM: boot time suspend selftest
    Date
    On Thursday, 29 of May 2008, David Brownell wrote:
    > From: David Brownell <dbrownell@users.sourceforge.net>
    >
    > Boot-time test for system suspend states (STR or standby). The generic
    > RTC framework triggers wakeup alarms, which are used to exit those states.
    >
    > - Measures some aspects of suspend time ... this uses "jiffies" until
    > someone converts it to use a timebase that works properly even while
    > timer IRQs are disabled.
    >
    > - Triggered by a command line parameter. By default nothing even
    > vaguely troublesome will happen, but "test_suspend=mem" will give
    > you a brief STR test during system boot. (Or you may need to use
    > "test_suspend=standby" instead, if your hardware needs that.)
    >
    > This isn't without problems. It fires early enough during boot that for
    > example both PCMCIA and MMC stacks have misbehaved. The workaround in
    > those cases was to boot without such media cards inserted.

    Two questions:

    1) How is it related to the analogous patch in the Ingo's tree?
    2) Does it apply to the current linux-next?

    Thanks,
    Rafael


    > Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
    > ---
    > I've used this on some ARM boards, and Ingo says it's been a big
    > help avoiding (upstream) regressions for x86.git work. Based on
    > some early work from Pavel, who wanted a pony. ;)
    >
    > Documentation/kernel-parameters.txt | 9 +
    > kernel/power/Kconfig | 11 ++
    > kernel/power/main.c | 185 ++++++++++++++++++++++++++++++++++
    > 3 files changed, 204 insertions(+), 1 deletion(-)
    >
    > --- a/Documentation/kernel-parameters.txt 2008-05-29 13:14:07.000000000 -0700
    > +++ b/Documentation/kernel-parameters.txt 2008-05-29 13:14:08.000000000 -0700
    > @@ -87,7 +87,8 @@ parameter is applicable:
    > SH SuperH architecture is enabled.
    > SMP The kernel is an SMP kernel.
    > SPARC Sparc architecture is enabled.
    > - SWSUSP Software suspend is enabled.
    > + SWSUSP Software suspend (hibernation) is enabled.
    > + SUSPEND System suspend states are enabled.
    > TS Appropriate touchscreen support is enabled.
    > USB USB support is enabled.
    > USBHID USB Human Interface Device support is enabled.
    > @@ -2035,6 +2036,12 @@ and is between 256 and 4096 characters.
    >
    > tdfx= [HW,DRM]
    >
    > + test_suspend= [SUSPEND]
    > + Specify "mem" (for Suspend-to-RAM) or "standby" (for
    > + standby suspend) as the system sleep state to briefly
    > + enter during system startup. The system is woken from
    > + this state using a wakeup-capable RTC alarm.
    > +
    > thash_entries= [KNL,NET]
    > Set number of hash buckets for TCP connection
    >
    > --- a/kernel/power/Kconfig 2008-05-29 13:14:07.000000000 -0700
    > +++ b/kernel/power/Kconfig 2008-05-29 13:14:08.000000000 -0700
    > @@ -94,6 +94,17 @@ config SUSPEND
    > powered and thus its contents are preserved, such as the
    > suspend-to-RAM state (e.g. the ACPI S3 state).
    >
    > +config PM_TEST_SUSPEND
    > + bool "Test suspend/resume and wakealarm during bootup"
    > + depends on SUSPEND && PM_DEBUG && RTC_LIB=y
    > + ---help---
    > + This option will let you suspend your machine during bootup, and
    > + make it wake up a few seconds later using an RTC wakeup alarm.
    > + Enable this with a kernel parameter like "test_suspend=mem".
    > +
    > + You probably want to have your system's RTC driver statically
    > + linked, ensuring that it's available when this test runs.
    > +
    > config SUSPEND_FREEZER
    > bool "Enable freezer for suspend to RAM/standby" \
    > if ARCH_WANTS_FREEZER_CONTROL || BROKEN
    > --- a/kernel/power/main.c 2008-05-29 13:14:07.000000000 -0700
    > +++ b/kernel/power/main.c 2008-05-29 13:14:08.000000000 -0700
    > @@ -132,6 +132,52 @@ static inline int suspend_test(int level
    >
    > #ifdef CONFIG_SUSPEND
    >
    > +#ifdef CONFIG_PM_TEST_SUSPEND
    > +
    > +/*
    > + * We test the system suspend code by setting an RTC wakealarm a short
    > + * time in the future, then suspending. Suspending the devices won't
    > + * normally take long ... some systems only need a few milliseconds.
    > + *
    > + * The time it takes is system-specific though, so when we test this
    > + * during system bootup we allow a LOT of time.
    > + */
    > +#define TEST_SUSPEND_SECONDS 5
    > +
    > +static unsigned long suspend_test_start_time;
    > +
    > +static void suspend_test_start(void)
    > +{
    > + /* FIXME Use better timebase than "jiffies", ideally a clocksource.
    > + * What we want is a hardware counter that will work correctly even
    > + * during the irqs-are-off stages of the suspend/resume cycle...
    > + */
    > + suspend_test_start_time = jiffies;
    > +}
    > +
    > +static void suspend_test_finish(const char *label)
    > +{
    > + long nj = jiffies - suspend_test_start_time;
    > + unsigned msec;
    > +
    > + msec = jiffies_to_msecs((nj >= 0) ? nj : -nj);
    > + pr_info("PM: %s took %d.%03d seconds\n", label,
    > + msec / 1000, msec % 1000);
    > + WARN_ON_ONCE(msec > (TEST_SUSPEND_SECONDS * 1000));
    > +}
    > +
    > +#else
    > +
    > +static void suspend_test_start(void)
    > +{
    > +}
    > +
    > +static void suspend_test_finish(const char *label)
    > +{
    > +}
    > +
    > +#endif
    > +
    > /* This is just an arbitrary number */
    > #define FREE_PAGE_NUMBER (100)
    >
    > @@ -264,11 +310,14 @@ int suspend_devices_and_enter(suspend_st
    > goto Close;
    > }
    > suspend_console();
    > +
    > + suspend_test_start();
    > error = device_suspend(PMSG_SUSPEND);
    > if (error) {
    > printk(KERN_ERR "PM: Some devices failed to suspend\n");
    > goto Resume_console;
    > }
    > + suspend_test_finish("suspend devices");
    >
    > if (suspend_test(TEST_DEVICES))
    > goto Resume_devices;
    > @@ -291,7 +340,9 @@ int suspend_devices_and_enter(suspend_st
    > if (suspend_ops->finish)
    > suspend_ops->finish();
    > Resume_devices:
    > + suspend_test_start();
    > device_resume();
    > + suspend_test_finish("resume devices");
    > Resume_console:
    > resume_console();
    > Close:
    > @@ -515,3 +566,137 @@ static int __init pm_init(void)
    > }
    >
    > core_initcall(pm_init);
    > +
    > +
    > +#ifdef CONFIG_PM_TEST_SUSPEND
    > +
    > +#include <linux/rtc.h>
    > +
    > +/*
    > + * To test system suspend, we need a hands-off mechanism to resume the
    > + * system. RTCs wake alarms are a common self-contained mechanism.
    > + */
    > +
    > +static void __init test_wakealarm(struct rtc_device *rtc, suspend_state_t state)
    > +{
    > + static char err_readtime [] __initdata =
    > + KERN_ERR "PM: can't read %s time, err %d\n";
    > + static char err_wakealarm [] __initdata =
    > + KERN_ERR "PM: can't set %s wakealarm, err %d\n";
    > + static char err_suspend [] __initdata =
    > + KERN_ERR "PM: suspend test failed, error %d\n";
    > + static char info_test [] __initdata =
    > + KERN_INFO "PM: test RTC wakeup from '%s' suspend\n";
    > +
    > + unsigned long now;
    > + struct rtc_wkalrm alm;
    > + int status;
    > +
    > + /* this may fail if the RTC hasn't been initialized */
    > + status = rtc_read_time(rtc, &alm.time);
    > + if (status < 0) {
    > + printk(err_readtime, rtc->dev.bus_id, status);
    > + return;
    > + }
    > + rtc_tm_to_time(&alm.time, &now);
    > +
    > + memset(&alm, 0, sizeof alm);
    > + rtc_time_to_tm(now + TEST_SUSPEND_SECONDS, &alm.time);
    > + alm.enabled = true;
    > +
    > + status = rtc_set_alarm(rtc, &alm);
    > + if (status < 0) {
    > + printk(err_wakealarm, rtc->dev.bus_id, status);
    > + return;
    > + }
    > +
    > + if (state == PM_SUSPEND_MEM) {
    > + printk(info_test, pm_states[state]);
    > + status = pm_suspend(state);
    > + if (status == -ENODEV)
    > + state = PM_SUSPEND_STANDBY;
    > + }
    > + if (state == PM_SUSPEND_STANDBY) {
    > + printk(info_test, pm_states[state]);
    > + status = pm_suspend(state);
    > + }
    > + if (status < 0)
    > + printk(err_suspend, status);
    > +}
    > +
    > +static int __init has_wakealarm(struct device *dev, void *name_ptr)
    > +{
    > + struct rtc_device *candidate = to_rtc_device(dev);
    > +
    > + if (!candidate->ops->set_alarm)
    > + return 0;
    > + if (!device_may_wakeup(candidate->dev.parent))
    > + return 0;
    > +
    > + *(char **)name_ptr = dev->bus_id;
    > + return 1;
    > +}
    > +
    > +/*
    > + * Kernel options like "test_suspend=mem" force suspend/resume sanity tests
    > + * at startup time. They're normally disabled, for faster boot and because
    > + * we can't know which states really work on this particular system.
    > + */
    > +static suspend_state_t test_state __initdata = PM_SUSPEND_ON;
    > +
    > +static char warn_bad_state[] __initdata =
    > + KERN_WARNING "PM: can't test '%s' suspend state\n";
    > +
    > +static int __init setup_test_suspend(char *value)
    > +{
    > + unsigned i;
    > +
    > + /* "=mem" ==> "mem" */
    > + value++;
    > + for (i = 0; i < PM_SUSPEND_MAX; i++) {
    > + if (!pm_states[i])
    > + continue;
    > + if (strcmp(pm_states[i], value) != 0)
    > + continue;
    > + test_state = (__force suspend_state_t) i;
    > + return 0;
    > + }
    > + printk(warn_bad_state, value);
    > + return 0;
    > +}
    > +__setup("test_suspend", setup_test_suspend);
    > +
    > +static int __init test_suspend(void)
    > +{
    > + static char warn_no_rtc[] __initdata =
    > + KERN_WARNING "PM: no wakealarm-capable RTC driver is ready\n";
    > +
    > + char *pony = NULL;
    > + struct rtc_device *rtc = NULL;
    > +
    > + /* PM is initialized by now; is that state testable? */
    > + if (test_state == PM_SUSPEND_ON)
    > + goto done;
    > + if (!valid_state(test_state)) {
    > + printk(warn_bad_state, pm_states[test_state]);
    > + goto done;
    > + }
    > +
    > + /* RTCs have initialized by now too ... can we use one? */
    > + class_find_device(rtc_class, &pony, has_wakealarm);
    > + if (pony)
    > + rtc = rtc_class_open(pony);
    > + if (!rtc) {
    > + printk(warn_no_rtc);
    > + goto done;
    > + }
    > +
    > + /* go for it */
    > + test_wakealarm(rtc, test_state);
    > + rtc_class_close(rtc);
    > +done:
    > + return 0;
    > +}
    > +late_initcall(test_suspend);
    > +
    > +#endif /* CONFIG_PM_TEST_SUSPEND */


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