* [PATCH] powerpc/mpic_timer: fix the time calculation is not accurate
@ 2013-12-23 2:33 Dongsheng Wang
2013-12-27 23:59 ` Scott Wood
0 siblings, 1 reply; 3+ messages in thread
From: Dongsheng Wang @ 2013-12-23 2:33 UTC (permalink / raw)
To: scottwood, galak; +Cc: linuxppc-dev, Wang Dongsheng
From: Wang Dongsheng <dongsheng.wang@freescale.com>
When the timer GTCCR toggle bit is inverted, we calculated the rest
of the time is not accurate. So we need to ignore this bit.
Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
diff --git a/arch/powerpc/sysdev/mpic_timer.c b/arch/powerpc/sysdev/mpic_timer.c
index 22d7d57..0fb70c9 100644
--- a/arch/powerpc/sysdev/mpic_timer.c
+++ b/arch/powerpc/sysdev/mpic_timer.c
@@ -41,6 +41,7 @@
#define MPIC_TIMER_TCR_ROVR_OFFSET 24
#define TIMER_STOP 0x80000000
+#define GTCCR_TOG 0x80000000
#define TIMERS_PER_GROUP 4
#define MAX_TICKS (~0U >> 1)
#define MAX_TICKS_CASCADE (~0U)
@@ -96,8 +97,15 @@ static void convert_ticks_to_time(struct timer_group_priv *priv,
time->tv_sec = (__kernel_time_t)div_u64(ticks, priv->timerfreq);
tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
- time->tv_usec = (__kernel_suseconds_t)
- div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
+ time->tv_usec = 0;
+
+ /*
+ * In some cases tmp_sec may be greater than ticks, because in the
+ * process of calculation ticks and tmp_sec will be rounded.
+ */
+ if (tmp_sec <= ticks)
+ time->tv_usec = (__kernel_suseconds_t)
+ div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
return;
}
@@ -327,11 +335,13 @@ void mpic_get_remain_time(struct mpic_timer *handle, struct timeval *time)
casc_priv = priv->timer[handle->num].cascade_handle;
if (casc_priv) {
tmp_ticks = in_be32(&priv->regs[handle->num].gtccr);
+ tmp_ticks &= ~GTCCR_TOG;
ticks = ((u64)tmp_ticks & UINT_MAX) * (u64)MAX_TICKS_CASCADE;
tmp_ticks = in_be32(&priv->regs[handle->num - 1].gtccr);
ticks += tmp_ticks;
} else {
ticks = in_be32(&priv->regs[handle->num].gtccr);
+ ticks &= ~GTCCR_TOG;
}
convert_ticks_to_time(priv, ticks, time);
--
1.8.5
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] powerpc/mpic_timer: fix the time calculation is not accurate
2013-12-23 2:33 [PATCH] powerpc/mpic_timer: fix the time calculation is not accurate Dongsheng Wang
@ 2013-12-27 23:59 ` Scott Wood
2013-12-30 2:21 ` Dongsheng.Wang
0 siblings, 1 reply; 3+ messages in thread
From: Scott Wood @ 2013-12-27 23:59 UTC (permalink / raw)
To: Dongsheng Wang; +Cc: linuxppc-dev
On Mon, 2013-12-23 at 10:33 +0800, Dongsheng Wang wrote:
> From: Wang Dongsheng <dongsheng.wang@freescale.com>
>
> When the timer GTCCR toggle bit is inverted, we calculated the rest
> of the time is not accurate. So we need to ignore this bit.
>
> Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
>
> diff --git a/arch/powerpc/sysdev/mpic_timer.c b/arch/powerpc/sysdev/mpic_timer.c
> index 22d7d57..0fb70c9 100644
> --- a/arch/powerpc/sysdev/mpic_timer.c
> +++ b/arch/powerpc/sysdev/mpic_timer.c
> @@ -41,6 +41,7 @@
> #define MPIC_TIMER_TCR_ROVR_OFFSET 24
>
> #define TIMER_STOP 0x80000000
> +#define GTCCR_TOG 0x80000000
> #define TIMERS_PER_GROUP 4
> #define MAX_TICKS (~0U >> 1)
> #define MAX_TICKS_CASCADE (~0U)
> @@ -96,8 +97,15 @@ static void convert_ticks_to_time(struct timer_group_priv *priv,
> time->tv_sec = (__kernel_time_t)div_u64(ticks, priv->timerfreq);
> tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
>
> - time->tv_usec = (__kernel_suseconds_t)
> - div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
> + time->tv_usec = 0;
> +
> + /*
> + * In some cases tmp_sec may be greater than ticks, because in the
> + * process of calculation ticks and tmp_sec will be rounded.
> + */
> + if (tmp_sec <= ticks)
> + time->tv_usec = (__kernel_suseconds_t)
> + div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
I don't see how this part of the patch relates to the patch description.
-Scott
^ permalink raw reply [flat|nested] 3+ messages in thread
* RE: [PATCH] powerpc/mpic_timer: fix the time calculation is not accurate
2013-12-27 23:59 ` Scott Wood
@ 2013-12-30 2:21 ` Dongsheng.Wang
0 siblings, 0 replies; 3+ messages in thread
From: Dongsheng.Wang @ 2013-12-30 2:21 UTC (permalink / raw)
To: Scott Wood; +Cc: linuxppc-dev@lists.ozlabs.org
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2013-12-23 2:33 [PATCH] powerpc/mpic_timer: fix the time calculation is not accurate Dongsheng Wang
2013-12-27 23:59 ` Scott Wood
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