Patch "cpufreq: longhaul: Revert transition_delay_us to 200 ms" has been added to the 4.15-stable tree

This is a note to let you know that I've just added the patch titled

cpufreq: longhaul: Revert transition_delay_us to 200 ms

to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
cpufreq-longhaul-revert-transition_delay_us-to-200-ms.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Viresh Kumar <[email protected]>
Date: Thu, 7 Dec 2017 15:15:19 +0530
Subject: cpufreq: longhaul: Revert transition_delay_us to 200 ms

From: Viresh Kumar <[email protected]>

[ Upstream commit 1d0d064307cbfd8546841f6e9d94d02c55e45e1e ]

The commit e948bc8fbee0 ("cpufreq: Cap the default transition delay value to 10 ms") caused a regression on EPIA-M min-ITX computer where shutdown or reboot hangs occasionally with a print message like:

longhaul: Warning: Timeout while waiting for idle PCI bus
cpufreq: __target_index: Failed to change cpu frequency: -16

This probably happens because the cpufreq governor tries to change the frequency of the CPU faster than allowed by the hardware.

Before the above commit, the default transition delay was set to 200 ms for a transition_latency of 200000 ns. Lets revert back to that transition delay value to fix it. Note that several other transition delay values were tested like 20 ms and 30 ms and none of them have resolved system hang issue completely.

---
 drivers/cpufreq/longhaul.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -894,7 +894,7 @@ static int longhaul_cpu_init(struct cpuf
 	if ((longhaul_version != TYPE_LONGHAUL_V1) && (scale_voltage != 0))
 		longhaul_setup_voltagescaling();
 
-	policy->cpuinfo.transition_latency = 200000;	/* nsec */
+	policy->transition_delay_us = 200000;	/* usec */
 
 	return cpufreq_table_validate_and_show(policy, longhaul_table);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.15/cpufreq-longhaul-revert-transition_delay_us-to-200-ms.patch