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Date: Tue, 18 Feb 2014 08:29:34 +0530
From: Preeti Murthy <preeti.lkml@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
LKML <linux-kernel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Ingo Molnar <mingo@...nel.org>,
"H. Peter Anvin" <hpa@...or.com>,
Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Subject: Re: [GIT Pull] timer fixes for 3.14
Hi Thomas,
With regard to the patch: "tick: Clear broadcast pending bit when
switching to oneshot"
isn't BROADCAST_EXIT called atleast after initializing the high
resolution timers while
handling the broadcast IPI and before re-entering idle? This should
clear the cpu bit
in the pending mask right?
idle()
|__BROADCAST_ENTER
|__halt()
|__broadcast_ipi
|__init_highres()->clear oneshot mask
|__return from interrupt->BROADCAST_EXIT (clear pending mask)
|__re-enter idle
When the cpu re-enters idle and does a BROADCAST_ENTER again, the
pending mask is cleared
and hence should not trigger a WARN_ON().
Thanks
Regards
Preeti U Murthy
On Sun, Feb 16, 2014 at 12:51 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> Linus,
>
> please pull the latest timers-urgent-for-linus git tree from:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers-urgent-for-linus
>
> The following trilogy of patches brings you:
>
> * Fix for a long standing math overflow issue with HZ < 60
>
> * An onliner fix for a corner case in the dreaded tick broadcast
> mechanism affecting a certain range of AMD machines which are
> infested with the infamous automagic C1E power control misfeature
>
> * A fix for one of the ARM platforms which allows the kernel to
> proceed and boot instead of stupidly panicing for no good
> reason. The patch is slightly larger than necessary, but it's less
> ugly than the alternative 5 liner.
>
>
> Thanks,
>
> tglx
>
> ------------------>
> Mikulas Patocka (1):
> time: Fix overflow when HZ is smaller than 60
>
> Thomas Gleixner (1):
> tick: Clear broadcast pending bit when switching to oneshot
>
> Tim Kryger (1):
> clocksource: Kona: Print warning rather than panic
>
>
> drivers/clocksource/bcm_kona_timer.c | 54 ++++++++++++++++++----------------
> kernel/time/jiffies.c | 6 ++++
> kernel/time/tick-broadcast.c | 1 +
> 3 files changed, 35 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/clocksource/bcm_kona_timer.c b/drivers/clocksource/bcm_kona_timer.c
> index 974b2db..0595dc6 100644
> --- a/drivers/clocksource/bcm_kona_timer.c
> +++ b/drivers/clocksource/bcm_kona_timer.c
> @@ -99,31 +99,6 @@ kona_timer_get_counter(void *timer_base, uint32_t *msw, uint32_t *lsw)
> return;
> }
>
> -static void __init kona_timers_init(struct device_node *node)
> -{
> - u32 freq;
> - struct clk *external_clk;
> -
> - external_clk = of_clk_get_by_name(node, NULL);
> -
> - if (!IS_ERR(external_clk)) {
> - arch_timer_rate = clk_get_rate(external_clk);
> - clk_prepare_enable(external_clk);
> - } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
> - arch_timer_rate = freq;
> - } else {
> - panic("unable to determine clock-frequency");
> - }
> -
> - /* Setup IRQ numbers */
> - timers.tmr_irq = irq_of_parse_and_map(node, 0);
> -
> - /* Setup IO addresses */
> - timers.tmr_regs = of_iomap(node, 0);
> -
> - kona_timer_disable_and_clear(timers.tmr_regs);
> -}
> -
> static int kona_timer_set_next_event(unsigned long clc,
> struct clock_event_device *unused)
> {
> @@ -198,7 +173,34 @@ static struct irqaction kona_timer_irq = {
>
> static void __init kona_timer_init(struct device_node *node)
> {
> - kona_timers_init(node);
> + u32 freq;
> + struct clk *external_clk;
> +
> + if (!of_device_is_available(node)) {
> + pr_info("Kona Timer v1 marked as disabled in device tree\n");
> + return;
> + }
> +
> + external_clk = of_clk_get_by_name(node, NULL);
> +
> + if (!IS_ERR(external_clk)) {
> + arch_timer_rate = clk_get_rate(external_clk);
> + clk_prepare_enable(external_clk);
> + } else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
> + arch_timer_rate = freq;
> + } else {
> + pr_err("Kona Timer v1 unable to determine clock-frequency");
> + return;
> + }
> +
> + /* Setup IRQ numbers */
> + timers.tmr_irq = irq_of_parse_and_map(node, 0);
> +
> + /* Setup IO addresses */
> + timers.tmr_regs = of_iomap(node, 0);
> +
> + kona_timer_disable_and_clear(timers.tmr_regs);
> +
> kona_timer_clockevents_init();
> setup_irq(timers.tmr_irq, &kona_timer_irq);
> kona_timer_set_next_event((arch_timer_rate / HZ), NULL);
> diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
> index 7a925ba..a6a5bf5 100644
> --- a/kernel/time/jiffies.c
> +++ b/kernel/time/jiffies.c
> @@ -51,7 +51,13 @@
> * HZ shrinks, so values greater than 8 overflow 32bits when
> * HZ=100.
> */
> +#if HZ < 34
> +#define JIFFIES_SHIFT 6
> +#elif HZ < 67
> +#define JIFFIES_SHIFT 7
> +#else
> #define JIFFIES_SHIFT 8
> +#endif
>
> static cycle_t jiffies_read(struct clocksource *cs)
> {
> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
> index 43780ab..98977a5 100644
> --- a/kernel/time/tick-broadcast.c
> +++ b/kernel/time/tick-broadcast.c
> @@ -756,6 +756,7 @@ out:
> static void tick_broadcast_clear_oneshot(int cpu)
> {
> cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
> + cpumask_clear_cpu(cpu, tick_broadcast_pending_mask);
> }
>
> static void tick_broadcast_init_next_event(struct cpumask *mask,
> --
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