[PATCH 0/4] MIPS: Guest timekeeping improvements

From: James Hogan
Date: Fri Apr 22 2016 - 13:19:37 EST

These patches improve timekeeping of MIPS/Malta kernels running in a KVM

Patch 2 fixes malta frequency calculation under virtualisation,
especially on very slow targets (FPGA / emulators). Patch 1 is a minor
fix for something I noticed while writing patch 2.

Patch 3 drops the use of the PIT timer for Malta, which is slow to
emulate with KVM + QEMU.

Finally patch 4 calculates min_delta_ns of cevt-r4k dynamically to
handle virtualised environments with software emulated Count/Compare,
and where Count frequency may not be directly related to actual CPU
speed (and so the static value of 0x300 may be no good).

James Hogan (4):
MIPS: malta-time: Start GIC count before syncing to RTC
MIPS: malta-time: Take seconds into account
MIPS: malta-time: Don't use PIT timer for cevt/csrc
MIPS: cevt-r4k: Dynamically calculate min_delta_ns

arch/mips/Kconfig | 1 -
arch/mips/kernel/cevt-r4k.c | 82 +++++++++++++++++++++++++++++++++++++++-
arch/mips/mti-malta/malta-time.c | 50 +++++++++++++++---------
3 files changed, 113 insertions(+), 20 deletions(-)

Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx