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authorMagnus Damm <magnus.damm@gmail.com>2009-05-01 01:45:46 -0400
committerThomas Gleixner <tglx@linutronix.de>2009-05-02 05:45:15 -0400
commita25cbd045a2ffc42787d4dbcbb9c7118f5f42732 (patch)
treecefbaaf38cd09ffb3c96cacf2b93b6d9caaa4fe2
parent091438dd5668396328a3419abcbc6591159eb8d1 (diff)
clocksource: setup mult_orig in clocksource_enable()
Setup clocksource mult_orig in clocksource_enable(). Clocksource drivers can save power by using keeping the device clock disabled while the clocksource is unused. In practice this means that the enable() and disable() callbacks perform clk_enable() and clk_disable(). The enable() callback may also use clk_get_rate() to get the clock rate from the clock framework. This information can then be used to calculate the shift and mult variables. Currently the mult_orig variable is setup from mult at registration time only. This is conflicting with the above case since the clock is disabled and the mult variable is not yet calculated at the time of registration. Moving the mult_orig setup code to clocksource_enable() allows us to both handle the common case with no enable() callback and the mult-changed-after-enable() case. [ Impact: allow dynamic clock source usage ] Signed-off-by: Magnus Damm <damm@igel.co.jp> LKML-Reference: <20090501054546.8193.10688.sendpatchset@rx1.opensource.se> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--include/linux/clocksource.h10
-rw-r--r--kernel/time/clocksource.c3
2 files changed, 9 insertions, 4 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h
index 5a40d14daa9f..c56457c8334e 100644
--- a/include/linux/clocksource.h
+++ b/include/linux/clocksource.h
@@ -288,7 +288,15 @@ static inline cycle_t clocksource_read(struct clocksource *cs)
288 */ 288 */
289static inline int clocksource_enable(struct clocksource *cs) 289static inline int clocksource_enable(struct clocksource *cs)
290{ 290{
291 return cs->enable ? cs->enable(cs) : 0; 291 int ret = 0;
292
293 if (cs->enable)
294 ret = cs->enable(cs);
295
296 /* save mult_orig on enable */
297 cs->mult_orig = cs->mult;
298
299 return ret;
292} 300}
293 301
294/** 302/**
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index ecfd7b5187e0..80189f6f1c5a 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -402,9 +402,6 @@ int clocksource_register(struct clocksource *c)
402 unsigned long flags; 402 unsigned long flags;
403 int ret; 403 int ret;
404 404
405 /* save mult_orig on registration */
406 c->mult_orig = c->mult;
407
408 spin_lock_irqsave(&clocksource_lock, flags); 405 spin_lock_irqsave(&clocksource_lock, flags);
409 ret = clocksource_enqueue(c); 406 ret = clocksource_enqueue(c);
410 if (!ret) 407 if (!ret)