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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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