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>

4 files changed, 17 insertions, 37 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a123a731ec4e..d533c205eea4 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1739,17 +1739,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
                         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 e2b4f40ff69a..1c0f1067af73 100644
--- a/drivers/cpufreq/pcc-cpufreq.c
+++ b/drivers/cpufreq/pcc-cpufreq.c
@@ -213,6 +213,7 @@ static int pcc_cpufreq_target(struct cpufreq_policy *policy,
                 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 @@ static int pcc_cpufreq_target(struct cpufreq_policy *policy,
         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 0023c7d40a51..e10b646634d7 100644
--- a/drivers/cpufreq/powernow-k8.c
+++ b/drivers/cpufreq/powernow-k8.c
@@ -964,14 +964,9 @@ static int transition_frequency_fidvid(struct powernow_k8_data *data,
         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 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)