Ingo noted that the description of clocks_calc_max_nsecs()'s
50% safety margin was somewhat circular. So this patch tries
to improve the comment to better explain what we mean by the
50% safety margin and why we need it.
Cc: Ingo Molnar <mi...@kernel.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Prarit Bhargava <pra...@redhat.com>
Cc: Richard Cochran <richardcoch...@gmail.com>
Signed-off-by: John Stultz <john.stu...@linaro.org>
---
kernel/time/clocksource.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index c3be3c7..15facb1 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -472,8 +472,11 @@ static u32 clocksource_max_adjustment(struct clocksource
*cs)
* @max_cyc: maximum cycle value before potential overflow (does not include
* any safety margin)
*
- * NOTE: This function includes a safety margin of 50%, so that bad clock
values
- * can be detected.
+ * NOTE: This function includes a safety margin of 50%, in other words, we
+ * return half the number of nanoseconds the hardware counter can technically
+ * cover. This is done so that we can potentially detect problems caused by
+ * delayed timers or bad hardware, which might result in time intervals that
+ * are larger then what the math used can handle without overflows.
*/
u64 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64
*max_cyc)
{
--
1.9.1
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