[ARM] twd: Fix prescaler getting cleared by set_mode

Change-Id: I98d4b02feeb9784591504c59a82058a58bbd038e
Signed-off-by: Colin Cross <ccross@android.com>

diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
index 2b4f92788c0e11c1286787912994750372f07912..a0db5474bdbe7cd44715d9f9ff68e4344c69f1dd 100644 (file)
--- a/arch/arm/kernel/smp_twd.c
+++ b/arch/arm/kernel/smp_twd.c
@@ -31,22 +31,23 @@ static unsigned long twd_target_rate;
 static void twd_set_mode(enum clock_event_mode mode,
                        struct clock_event_device *clk)
 {
-       unsigned long ctrl;
+       unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
+       ctrl |= TWD_TIMER_CONTROL_PRESCALE_MASK;
 
        switch (mode) {
        case CLOCK_EVT_MODE_PERIODIC:
                /* timer load already set up */
-               ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
+               ctrl |= TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
                        | TWD_TIMER_CONTROL_PERIODIC;
                break;
        case CLOCK_EVT_MODE_ONESHOT:
                /* period set, and timer enabled in 'next_event' hook */
-               ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
+               ctrl |= TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
                break;
        case CLOCK_EVT_MODE_UNUSED:
        case CLOCK_EVT_MODE_SHUTDOWN:
        default:
-               ctrl = 0;
+               break;
        }
 
        __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
@@ -145,9 +146,8 @@ static void __cpuinit twd_calibrate_rate(unsigned long target_rate,
                        twd_target_rate = target_rate;
 
                        cpu_rate = twd_timer_rate * periphclk_prescaler;
-                       twd_recalc_prescaler(cpu_rate);
-
                        twd_timer_rate = twd_target_rate;
+                       twd_recalc_prescaler(cpu_rate);
                }
 
                printk("%lu.%02luMHz.\n", twd_timer_rate / 1000000,