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authorSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>2014-04-29 00:24:42 +0530
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-04-29 01:22:53 +0200
commit3221e55b72359c44ed75afbcf707710af5bc2d59 (patch)
tree85c6770b0fa26e90f10cc8e8c51d5cb2c8504bb7 /drivers/cpufreq
parent237ede16ba5bcd4d6c612ea280518c48ca31986c (diff)
cpufreq: powernow-k6: Fix double invocation of cpufreq_freq_transition_begin/end
During frequency transitions, the cpufreq core takes the responsibility of invoking cpufreq_freq_transition_begin() and cpufreq_freq_transition_end() for those cpufreq drivers that define the ->target_index callback but don't set the ASYNC_NOTIFICATION flag. The powernow-k6 cpufreq driver falls under this category, but this driver was invoking the _begin() and _end() APIs itself around frequency transitions, which led to double invocation of the _begin() API. The _begin API makes contending callers wait until the previous invocation is complete. Hence, the powernow-k6 driver ended up waiting on itself, leading to system hangs during boot. Fix this by removing the calls to the _begin() and _end() APIs from the powernow-k6 driver, since they rightly belong to the cpufreq core. (Note that during ->exit(), the powernow-k6 driver sets the frequency without any help from the cpufreq core. So add explicit calls to the _begin() and _end() APIs around that frequency transition alone, to take care of that special case. Also, add a missing 'break' statement there.) Fixes: 12478cf0c55e (cpufreq: Make sure frequency transitions are serialized) Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpufreq')
-rw-r--r--drivers/cpufreq/powernow-k6.c20
1 files changed, 11 insertions, 9 deletions
diff --git a/drivers/cpufreq/powernow-k6.c b/drivers/cpufreq/powernow-k6.c
index 695a68cfdcd4..78904e6ca4a0 100644
--- a/drivers/cpufreq/powernow-k6.c
+++ b/drivers/cpufreq/powernow-k6.c
@@ -138,22 +138,14 @@ static void powernow_k6_set_cpu_multiplier(unsigned int best_i)
static int powernow_k6_target(struct cpufreq_policy *policy,
unsigned int best_i)
{
- struct cpufreq_freqs freqs;
if (clock_ratio[best_i].driver_data > max_multiplier) {
printk(KERN_ERR PFX "invalid target frequency\n");
return -EINVAL;
}
- freqs.old = busfreq * powernow_k6_get_cpu_multiplier();
- freqs.new = busfreq * clock_ratio[best_i].driver_data;
-
- cpufreq_freq_transition_begin(policy, &freqs);
-
powernow_k6_set_cpu_multiplier(best_i);
- cpufreq_freq_transition_end(policy, &freqs, 0);
-
return 0;
}
@@ -229,8 +221,18 @@ static int powernow_k6_cpu_exit(struct cpufreq_policy *policy)
unsigned int i;
for (i = 0; (clock_ratio[i].frequency != CPUFREQ_TABLE_END); i++) {
- if (clock_ratio[i].driver_data == max_multiplier)
+ if (clock_ratio[i].driver_data == max_multiplier) {
+ struct cpufreq_freqs freqs;
+
+ freqs.old = policy->cur;
+ freqs.new = clock_ratio[i].frequency;
+ freqs.flags = 0;
+
+ cpufreq_freq_transition_begin(policy, &freqs);
powernow_k6_target(policy, i);
+ cpufreq_freq_transition_end(policy, &freqs, 0);
+ break;
+ }
}
return 0;
}