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>
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a123a73..d533c20 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1739,17 +1739,8 @@
pr_err("%s: Failed to change cpu frequency: %d\n",
__func__, retval);
- if (notify) {
- /*
- * Notify with old freq in case we failed to change
- * frequency
- */
- if (retval)
- freqs.new = freqs.old;
-
- cpufreq_notify_transition(policy, &freqs,
- CPUFREQ_POSTCHANGE);
- }
+ if (notify)
+ cpufreq_notify_post_transition(policy, &freqs, retval);
}
out:
diff --git a/drivers/cpufreq/pcc-cpufreq.c b/drivers/cpufreq/pcc-cpufreq.c
index e2b4f40..1c0f1067 100644
--- a/drivers/cpufreq/pcc-cpufreq.c
+++ b/drivers/cpufreq/pcc-cpufreq.c
@@ -213,6 +213,7 @@
cpu, target_freq,
(pcch_virt_addr + pcc_cpu_data->input_offset));
+ freqs.old = policy->cur;
freqs.new = target_freq;
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
@@ -228,25 +229,20 @@
memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
status = ioread16(&pcch_hdr->status);
+ iowrite16(0, &pcch_hdr->status);
+
+ cpufreq_notify_post_transition(policy, &freqs, status != CMD_COMPLETE);
+ spin_unlock(&pcc_lock);
+
if (status != CMD_COMPLETE) {
pr_debug("target: FAILED for cpu %d, with status: 0x%x\n",
cpu, status);
- goto cmd_incomplete;
+ return -EINVAL;
}
- iowrite16(0, &pcch_hdr->status);
- cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
pr_debug("target: was SUCCESSFUL for cpu %d\n", cpu);
- spin_unlock(&pcc_lock);
return 0;
-
-cmd_incomplete:
- freqs.new = freqs.old;
- cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
- iowrite16(0, &pcch_hdr->status);
- spin_unlock(&pcc_lock);
- return -EINVAL;
}
static int pcc_get_offset(int cpu)
diff --git a/drivers/cpufreq/powernow-k8.c b/drivers/cpufreq/powernow-k8.c
index 0023c7d..e10b646 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -964,14 +964,9 @@
cpufreq_cpu_put(policy);
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
-
res = transition_fid_vid(data, fid, vid);
- if (res)
- freqs.new = freqs.old;
- else
- freqs.new = find_khz_freq_from_fid(data->currfid);
+ cpufreq_notify_post_transition(policy, &freqs, res);
- cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
return res;
}
diff --git a/drivers/cpufreq/unicore2-cpufreq.c b/drivers/cpufreq/unicore2-cpufreq.c
index 653ae29..86f6cfe 100644
--- a/drivers/cpufreq/unicore2-cpufreq.c
+++ b/drivers/cpufreq/unicore2-cpufreq.c
@@ -46,20 +46,18 @@
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;
+
+ freqs.old = policy->cur;
+ freqs.new = target_freq;
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
+ ret = clk_set_rate(mclk, target_freq * 1000);
+ cpufreq_notify_post_transition(policy, &freqs, ret);
- if (!clk_set_rate(mclk, target_freq * 1000)) {
- freqs.old = cur;
- freqs.new = target_freq;
- }
-
- cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
-
- return 0;
+ return ret;
}
static int __init ucv2_cpu_init(struct cpufreq_policy *policy)