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>

diff --git a/arch/arm/kernel/sched_clock.c b/arch/arm/kernel/sched_clock.c
index bd6f56b9ec2101534b7477c11c9f6ef0a3a6e68b..040168e8a60dd38017b9952d013d372aebdc50bf 100644 (file)
--- 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);