summaryrefslogtreecommitdiff
path: root/drivers/cpufreq/unicore2-cpufreq.c
diff options
context:
space:
mode:
authorViresh Kumar <viresh.kumar@linaro.org>2013-12-02 11:04:13 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-01-06 01:43:44 +0100
commitab1b1c4e8223f9ee66aa93aaf64c36e77cadffac (patch)
treeb592025459590a4564fd8e7760707c7d77a159e1 /drivers/cpufreq/unicore2-cpufreq.c
parentf7ba3b41e27129575201f0f9656e83fb67e86c3b (diff)
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 <viresh.kumar@linaro.org> [rjw: Folded 3 patches into one, rebased unicore2 changes] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq/unicore2-cpufreq.c')
-rw-r--r--drivers/cpufreq/unicore2-cpufreq.c16
1 files changed, 7 insertions, 9 deletions
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)