ARM: sched_clock: allow changing to higher frequency counter

Allow multiple calls to setup_sched_clock and switch to the new counter
if it is higher frequency.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
index bd6f56b9ec21..040168e8a60d 100644
--- a/arch/arm/kernel/sched_clock.c
+++ b/arch/arm/kernel/sched_clock.c
@@ -20,6 +20,7 @@ struct clock_data {
         u64 epoch_ns;
         u32 epoch_cyc;
         u32 epoch_cyc_copy;
+        unsigned long rate;
         u32 mult;
         u32 shift;
         bool suspended;
@@ -113,11 +114,14 @@ void __init setup_sched_clock(u32 (*read)(void), int bits, unsigned long rate)
         u64 res, wrap;
         char r_unit;
 
+        if (cd.rate > rate)
+                return;
+
         BUG_ON(bits > 32);
         WARN_ON(!irqs_disabled());
-        WARN_ON(read_sched_clock != jiffy_sched_clock_read);
         read_sched_clock = read;
         sched_clock_mask = (1 << bits) - 1;
+        cd.rate = rate;
 
         /* calculate the mult/shift to convert counter ticks to ns. */
         clocks_calc_mult_shift(&cd.mult, &cd.shift, rate, NSEC_PER_SEC, 0);