From ab1b1c4e8223f9ee66aa93aaf64c36e77cadffac Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Mon, 2 Dec 2013 11:04:13 +0530 Subject: cpufreq: send new set of notification for transition failures In the current code, if we fail during a frequency transition, we simply send the POSTCHANGE notification with the old frequency. This isn't enough. One of the core users of these notifications is the code responsible for keeping loops_per_jiffy aligned with frequency changes. And mostly it is written as: if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { update-loops-per-jiffy... } So, suppose we are changing to a higher frequency and failed during transition, then following will happen: - CPUFREQ_PRECHANGE notification with freq-new > freq-old - CPUFREQ_POSTCHANGE notification with freq-new == freq-old The first one will update loops_per_jiffy and second one will do nothing. Even if we send the 2nd notification by exchanging values of freq-new and old, some users of these notifications might get unstable. This can be fixed by simply calling cpufreq_notify_post_transition() with error code and this routine will take care of sending notifications in the correct order. Signed-off-by: Viresh Kumar [rjw: Folded 3 patches into one, rebased unicore2 changes] Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/unicore2-cpufreq.c | 16 +++++++--------- 1 file changed, 7 insertions(+), 9 deletions(-) (limited to 'drivers/cpufreq/unicore2-cpufreq.c') diff --git a/drivers/cpufreq/unicore2-cpufreq.c b/drivers/cpufreq/unicore2-cpufreq.c index 653ae2955b55..86f6cfec2e09 100644 --- a/drivers/cpufreq/unicore2-cpufreq.c +++ b/drivers/cpufreq/unicore2-cpufreq.c @@ -46,20 +46,18 @@ static int ucv2_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { - unsigned int cur = ucv2_getspeed(0); struct cpufreq_freqs freqs; struct clk *mclk = clk_get(NULL, "MAIN_CLK"); + int ret; - cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); - - if (!clk_set_rate(mclk, target_freq * 1000)) { - freqs.old = cur; - freqs.new = target_freq; - } + freqs.old = policy->cur; + freqs.new = target_freq; - cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); + cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); + ret = clk_set_rate(mclk, target_freq * 1000); + cpufreq_notify_post_transition(policy, &freqs, ret); - return 0; + return ret; } static int __init ucv2_cpu_init(struct cpufreq_policy *policy) -- cgit