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

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

drivers/cpufreq/cpufreq.c

+2 −11
Original line number Diff line number Diff line
@@ -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:

drivers/cpufreq/pcc-cpufreq.c

+7 −11
Original line number Diff line number Diff line
@@ -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)

drivers/cpufreq/powernow-k8.c

+1 −6
Original line number Diff line number Diff line
@@ -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;

}

drivers/cpufreq/unicore2-cpufreq.c

+7 −9
Original line number Diff line number Diff line
@@ -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.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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