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MIPS: Don't overflow cevt-r4k.c calculations at high clock rates.

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The 'mult' element of struct clock_event_device must never be wider
than 32-bits.  If it were, it would get truncated when used by
clockevent_delta2ns() when this calls do_div().

We can meet this requirement by using clockevent_set_clock() to set
the MULT and SHIFT values.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1253/
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
David Daney 2010-05-19 10:40:53 -07:00 committed by Ralf Baechle
parent 6165df9808
commit 4d2b11252b
1 changed files with 2 additions and 3 deletions
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5
arch/mips/kernel/cevt-r4k.c
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@ -163,7 +163,6 @@ int c0_compare_int_usable(void)
int __cpuinit r4k_clockevent_init(void)
{
uint64_t mips_freq = mips_hpt_frequency;
unsigned int cpu = smp_processor_id();
struct clock_event_device *cd;
unsigned int irq;
@ -188,9 +187,9 @@ int __cpuinit r4k_clockevent_init(void)
cd->name = "MIPS";
cd->features = CLOCK_EVT_FEAT_ONESHOT;
clockevent_set_clock(cd, mips_hpt_frequency);
/* Calculate the min / max delta */
cd->mult = div_sc((unsigned long) mips_freq, NSEC_PER_SEC, 32);
cd->shift = 32;
cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
cd->min_delta_ns = clockevent_delta2ns(0x300, cd);