Commit ab1b1c4e authored by Viresh Kumar's avatar Viresh Kumar Committed by Rafael J. Wysocki

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: default avatarViresh Kumar <viresh.kumar@linaro.org>
[rjw: Folded 3 patches into one, rebased unicore2 changes]
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent f7ba3b41
......@@ -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:
......
......@@ -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)
......
......@@ -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;
}
......
......@@ -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)
......
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