Konstantin Baydarov <[email protected]> writes:
> Eric, actually calling hpet_disable_int() under
> CLOCK_EVT_MODE_SHUTDOWN is not enough, because
> HPET might not be shutdown at all (we might want to use HPET and don't
> want to use LAPIC timer or in some cases HPET is used as broadcast
> device with LAPIC timers enabled). So, somehow, we should call
> hpet_set_mode with CLOCK_EVT_MODE_SHUTDOWN as an argument before
> machine_kexec. To solve this I've added timekeeping_shutdown() to
> timekeeping.c that calls clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND,
> NULL). Function timekeeping_shutdown() is called from sysdev_shutdown().
Is suspend the right thing? The fact that time keeping seems
to be reinventing the standard infrastructure for shutting
down instead of just reusing it has me a bit confused.
Regardless hooking into the shutdown is the right thing
to do here.
> Also If we are adding hpet_disable_int() under
> CLOCK_EVT_MODE_SHUTDOWN we have to add hpet_enable_int under
> CLOCK_EVT_MODE_PERIODIC and CLOCK_EVT_MODE_ONESHOT.
However that works. I just know that in the device tree we
have shutdown methods that are called on reboot and kexec
and the hpet needs one, and that is where the code belongs.
I was assuming that CLOCK_EVT_MODE_SHUTDOWN just mapped
to the shutdown method of the clock events or something else.
But it shutdown means something different in this context we
can certainly find a better place to hook into the device
tree and call shutdown methods. Especially if that will
make the code simpler.
> Also I've added call of hpet_disable_int() to machine_crash_shutdown()
> because, as you said, sysdev_shutdown() won't be called on crash before
> machine_kexec().
This is a design feature. machine_crash_shutdown is not really
supposed to disable any hardware. There is a very minimal set that we
haven't been able to figure out how to get the kernels initialization
routines to deal with properly. Which is a temporary justification
for not doing more now. If we can't find anyway to make the
initialization code more robust for the hpet we can revisit this.
> Also, as we have to make hpet_disable_int() global and call it from
> machine_crash_shutdown(), I suggest not to add hpet_disable_int() under
> CLOCK_EVT_MODE_SHUTDOWN. If we don't add hpet_disable_int() under
> CLOCK_EVT_MODE_SHUTDOWN - patch will be more smaller because we don't
> have to call clockevents_notify() and we don't have to add
> hpet_enable_int. We just have to add hpet_disable_int() call to
> timekeeping_shutdown(). But it's just suggestion - attached patch adds
> hpet_disable_int() under CLOCK_EVT_MODE_SHUTDOWN.
Please remove the CONFIG_KEXEC. We need to do this on a reboot also
so we don't confuse the BIOS. BIOS's frequently but not always
can just reset the board to avoid complications like this, but if
we need a shutdown method we need a shutdown method. The kexec
case just exercises things more.
Please can we ignore the machine_crash_shutdown path for the moment.
And revisit it again after we have the normal case fixed.
Adding hpet_disable_int into timekeeping_shutdown at first glance
looks like a layering and maintenance violation.
Eric
> Here is new version of fix. It still against kernel 2.6.23-rc3. Thanks.
>
> Signed-off-by: Konstantin Baydarov <[email protected]>
>
> arch/i386/kernel/crash.c | 4 ++++
> arch/i386/kernel/hpet.c | 33 +++++++++++++++++++++++++++++++++
> include/asm-i386/hpet.h | 3 +++
> kernel/time/timekeeping.c | 13 +++++++++++++
> 4 files changed, 53 insertions(+)
>
> Index: linux-2.6.23-rc3/arch/i386/kernel/hpet.c
> ===================================================================
> --- linux-2.6.23-rc3.orig/arch/i386/kernel/hpet.c
> +++ linux-2.6.23-rc3/arch/i386/kernel/hpet.c
> @@ -144,11 +144,35 @@ static void hpet_enable_int(void)
> {
> unsigned long cfg = hpet_readl(HPET_CFG);
>
> +#ifdef CONFIG_KEXEC
> + if (hpet_legacy_int_enabled)
> + return;
> +#endif
Why do we need this test only for kexec?
> +
> cfg |= HPET_CFG_LEGACY;
> hpet_writel(cfg, HPET_CFG);
> hpet_legacy_int_enabled = 1;
> }
>
> +#ifdef CONFIG_KEXEC
> +void hpet_disable_int(void)
> +{
> + unsigned long cfg;
> +
> + if (!hpet_legacy_int_enabled)
> + return;
> +
> + if (!is_hpet_capable())
> + return;
> +
> + cfg = hpet_readl(HPET_CFG);
> + cfg &= ~HPET_CFG_LEGACY;
> + hpet_writel(cfg, HPET_CFG);
> + hpet_legacy_int_enabled = 0;
> +
> +}
> +#endif
> +
> static void hpet_set_mode(enum clock_event_mode mode,
> struct clock_event_device *evt)
> {
> @@ -157,6 +181,9 @@ static void hpet_set_mode(enum clock_eve
>
> switch(mode) {
> case CLOCK_EVT_MODE_PERIODIC:
> +#ifdef CONFIG_KEXEC
> + hpet_enable_int();
> +#endif
> delta = ((uint64_t)(NSEC_PER_SEC/HZ)) * hpet_clockevent.mult;
> delta >>= hpet_clockevent.shift;
> now = hpet_readl(HPET_COUNTER);
> @@ -176,6 +203,9 @@ static void hpet_set_mode(enum clock_eve
> break;
>
> case CLOCK_EVT_MODE_ONESHOT:
> +#ifdef CONFIG_KEXEC
> + hpet_enable_int();
> +#endif
> cfg = hpet_readl(HPET_T0_CFG);
> cfg &= ~HPET_TN_PERIODIC;
> cfg |= HPET_TN_ENABLE | HPET_TN_32BIT;
> @@ -187,6 +217,9 @@ static void hpet_set_mode(enum clock_eve
> cfg = hpet_readl(HPET_T0_CFG);
> cfg &= ~HPET_TN_ENABLE;
> hpet_writel(cfg, HPET_T0_CFG);
> +#ifdef CONFIG_KEXEC
> + hpet_disable_int();
> +#endif
> break;
>
> case CLOCK_EVT_MODE_RESUME:
> Index: linux-2.6.23-rc3/include/asm-i386/hpet.h
> ===================================================================
> --- linux-2.6.23-rc3.orig/include/asm-i386/hpet.h
> +++ linux-2.6.23-rc3/include/asm-i386/hpet.h
> @@ -66,6 +66,9 @@
> extern unsigned long hpet_address;
> extern int is_hpet_enabled(void);
> extern int hpet_enable(void);
> +#ifdef CONFIG_KEXEC
> +extern void hpet_disable_int(void);
> +#endif
>
> #ifdef CONFIG_HPET_EMULATE_RTC
>
> Index: linux-2.6.23-rc3/arch/i386/kernel/crash.c
> ===================================================================
> --- linux-2.6.23-rc3.orig/arch/i386/kernel/crash.c
> +++ linux-2.6.23-rc3/arch/i386/kernel/crash.c
> @@ -24,6 +24,7 @@
> #include <asm/apic.h>
> #include <linux/kdebug.h>
> #include <asm/smp.h>
> +#include <asm/hpet.h>
>
> #include <mach_ipi.h>
>
> @@ -128,6 +129,9 @@ void machine_crash_shutdown(struct pt_re
>
> /* Make a note of crashing cpu. Will be used in NMI callback.*/
> crashing_cpu = safe_smp_processor_id();
> +#ifdef CONFIG_KEXEC
> + hpet_disable_int();
> +#endif
> nmi_shootdown_cpus();
> lapic_shutdown();
> #if defined(CONFIG_X86_IO_APIC)
> Index: linux-2.6.23-rc3/kernel/time/timekeeping.c
> ===================================================================
> --- linux-2.6.23-rc3.orig/kernel/time/timekeeping.c
> +++ linux-2.6.23-rc3/kernel/time/timekeeping.c
> @@ -335,8 +335,21 @@ static int timekeeping_suspend(struct sy
> return 0;
> }
>
> +#ifdef CONFIG_KEXEC
> +static int timekeeping_shutdown(struct sys_device *dev)
> +{
> + clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
Hmm. Do we want to add a CLOCK_EVT_NOTIFY_SHUTDOWN?
Would that make anything simpler?
> +// hpet_disable_int();
> +
> + return 0;
> +}
> +#endif
> +
> /* sysfs resume/suspend bits for timekeeping */
> static struct sysdev_class timekeeping_sysclass = {
> +#ifdef CONFIG_KEXEC
> + .shutdown = timekeeping_shutdown,
> +#endif
> .resume = timekeeping_resume,
> .suspend = timekeeping_suspend,
> set_kset_name("timekeeping"),
-
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