Following patch "cpufreq: make sure frequency transitions are serialized"
guarantees that we don't have any races while changing cpu frequency or sending
notifications. It handled a special case with CPUFREQ_ASYNC_NOTIFICATION flag
for drivers that don't complete their freq change from ->target() and exynos5440
driver is well adopted to it as well..
There is one more driver powernow-k8 that has similar implementation, schedules
a work for doing transitions. All is good if that work function does
notifications on every call to it and so the transition_ongoing count stays
stable. But there are chances that the work function may return without actually
doing the notifications, in which case transition_ongoing count will not be set
to zero and so no transitions would be possible after that.
This patch fixes powernow-k8 driver to get transition_ongoing count stable. It
does following to ensure proper working of this driver:
- return -EINPROGRESS from ->target() so that core doesn't mark transfer over at
the end of ->target().
- mark cpufreq_driver->flags with CPUFREQ_ASYNC_NOTIFICATION, so that core knows
that driver would terminate its transition.
- call cpufreq_transition_complete() whenever we are returning before sending
notifications
Hopefully things will work well after this patch, only compiled tested at my
end.
Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
---
drivers/cpufreq/powernow-k8.c | 47 +++++++++++++++++++++++++++++++------------
1 file changed, 34 insertions(+), 13 deletions(-)
diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 2344a9e..8215bbc 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -952,7 +952,7 @@ static int transition_frequency_fidvid(struct
powernow_k8_data *data,
if ((data->currvid == vid) && (data->currfid == fid)) {
pr_debug("target matches current values (fid 0x%x, vid 0x%x)\n",
fid, vid);
- return 0;
+ return -EALREADY;
}
pr_debug("cpu %d, changing to fid 0x%x, vid 0x%x\n",
@@ -993,22 +993,27 @@ static long powernowk8_target_fn(void *arg)
unsigned int newstate;
int ret;
- if (!data)
- return -EINVAL;
+ if (!data) {
+ ret = -EINVAL;
+ goto transition_complete;
+ }
checkfid = data->currfid;
checkvid = data->currvid;
if (pending_bit_stuck()) {
printk(KERN_ERR PFX "failing targ, change pending bit set\n");
- return -EIO;
+ ret = -EIO;
+ goto transition_complete;
}
pr_debug("targ: cpu %d, %d kHz, min %d, max %d, relation %d\n",
pol->cpu, targfreq, pol->min, pol->max, relation);
- if (query_current_values_with_pending_wait(data))
- return -EIO;
+ if (query_current_values_with_pending_wait(data)) {
+ ret = -EIO;
+ goto transition_complete;
+ }
pr_debug("targ: curr fid 0x%x, vid 0x%x\n",
data->currfid, data->currvid);
@@ -1022,25 +1027,36 @@ static long powernowk8_target_fn(void *arg)
}
if (cpufreq_frequency_table_target(pol, data->powernow_table,
- targfreq, relation, &newstate))
- return -EIO;
+ targfreq, relation, &newstate)) {
+ ret = -EIO;
+ goto transition_complete;
+ }
mutex_lock(&fidvid_mutex);
powernow_k8_acpi_pst_values(data, newstate);
ret = transition_frequency_fidvid(data, newstate);
+ mutex_unlock(&fidvid_mutex);
if (ret) {
- printk(KERN_ERR PFX "transition frequency failed\n");
- mutex_unlock(&fidvid_mutex);
- return 1;
+ /* Not a error case, just need to mark transition complete */
+ if (ret == -EALREADY) {
+ ret = 0;
+ } else {
+ printk(KERN_ERR PFX "transition frequency failed\n");
+ ret = 1;
+ }
+ goto transition_complete;
}
- mutex_unlock(&fidvid_mutex);
pol->cur = find_khz_freq_from_fid(data->currfid);
return 0;
+
+transition_complete:
+ cpufreq_transition_complete(pol);
+ return ret;
}
/* Driver entry point to switch to the target frequency */
@@ -1049,8 +1065,12 @@ static int powernowk8_target(struct cpufreq_policy *pol,
{
struct powernowk8_target_arg pta = { .pol = pol, .targfreq = targfreq,
.relation = relation };
+ int ret;
- return work_on_cpu(pol->cpu, powernowk8_target_fn, &pta);
+ ret = work_on_cpu(pol->cpu, powernowk8_target_fn, &pta);
+ if (!ret)
+ ret = -EINPROGRESS; /* Mark transition as In-progress */
+ return ret;
}
/* Driver entry point to verify the policy and range of frequencies */
@@ -1233,6 +1253,7 @@ static struct freq_attr *powernow_k8_attr[] = {
};
static struct cpufreq_driver cpufreq_amd64_driver = {
+ .flags = CPUFREQ_ASYNC_NOTIFICATION,
.verify = powernowk8_verify,
.target = powernowk8_target,
.bios_limit = acpi_processor_get_bios_limit,
--
1.7.12.rc2.18.g61b472e
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