Re: [PATCH] powerpc/powernv/idle: Round up latency and residency values
From: Gautham R Shenoy <hidden>
Date: 2017-08-24 04:35:33
Also in:
linux-pm
Hi Vaidy, On Thu, Aug 24, 2017 at 12:28:41AM +0530, Vaidyanathan Srinivasan wrote: Cc'ing Rafael and linux-pm list.
On PowerNV platforms, firmware provides exit latency and target residency for each of the idle states in nano seconds. Cpuidle framework expects the values in micro seconds. Round up to nearest micro seconds to avoid errors in cases where the values are defined as fractional micro seconds. Default idle state of 'snooze' has exit latency of zero. If other states have fractional micro second exit latency, they would get rounded down to zero micro second and make cpuidle framework choose deeper idle state when snooze loop is the right choice. Reported-by: Anton Blanchard <redacted> Signed-off-by: Vaidyanathan Srinivasan <redacted>
This looks good to me. Reviewed-by: Gautham R. Shenoy <redacted>
quoted hunk ↗ jump to hunk
--- drivers/cpuidle/cpuidle-powernv.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c index 42896a67aeae..5f3922392059 100644 --- a/drivers/cpuidle/cpuidle-powernv.c +++ b/drivers/cpuidle/cpuidle-powernv.c@@ -383,9 +383,9 @@ static int powernv_add_idle_states(void) * Firmware passes residency and latency values in ns. * cpuidle expects it in us. */ - exit_latency = latency_ns[i] / 1000; + exit_latency = DIV_ROUND_UP(latency_ns[i], 1000); if (!rc) - target_residency = residency_ns[i] / 1000; + target_residency = DIV_ROUND_UP(residency_ns[i], 1000); else target_residency = 0;-- 2.13.5