releases/4.14.7/powerpc-powernv-idle-round-up-latency-and-residency-values.patch

   1 From foo@baz Tue Dec 12 10:32:42 CET 2017
   2 From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
   3 Date: Thu, 24 Aug 2017 00:28:41 +0530
   4 Subject: powerpc/powernv/idle: Round up latency and residency values
   5
   6 From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
   7
   8
   9 [ Upstream commit 8d4e10e9ed9450e18fbbf6a8872be0eac9fd4999 ]
  10
  11 On PowerNV platforms, firmware provides exit latency and
  12 target residency for each of the idle states in nano
  13 seconds.  Cpuidle framework expects the values in micro
  14 seconds.  Round up to nearest micro seconds to avoid errors
  15 in cases where the values are defined as fractional micro
  16 seconds.
  17
  18 Default idle state of 'snooze' has exit latency of zero.  If
  19 other states have fractional micro second exit latency, they
  20 would get rounded down to zero micro second and make cpuidle
  21 framework choose deeper idle state when snooze loop is the
  22 right choice.
  23
  24 Reported-by: Anton Blanchard <anton@samba.org>
  25 Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
  26 Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
  27 Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
  28 Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
  29 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  30 ---
  31  drivers/cpuidle/cpuidle-powernv.c |    4 ++--
  32  1 file changed, 2 insertions(+), 2 deletions(-)
  33
  34 --- a/drivers/cpuidle/cpuidle-powernv.c
  35 +++ b/drivers/cpuidle/cpuidle-powernv.c
  36 @@ -384,9 +384,9 @@ static int powernv_add_idle_states(void)
  37                  * Firmware passes residency and latency values in ns.
  38                  * cpuidle expects it in us.
  39                  */
  40 -               exit_latency = latency_ns[i] / 1000;
  41 +               exit_latency = DIV_ROUND_UP(latency_ns[i], 1000);
  42                 if (!rc)
  43 -                       target_residency = residency_ns[i] / 1000;
  44 +                       target_residency = DIV_ROUND_UP(residency_ns[i], 1000);
  45                 else
  46                         target_residency = 0;
  47