linux-kernel - [RESEND PATCH] [CPUFREQ] EXYNOS: bugfix on retrieving old

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Date:	Fri, 20 Jul 2012 11:54:02 +0900
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	linux-kernel@...r.kernel.org
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, cpufreq@...r.kernel.org,
	linux-pm@...r.kernel.org, Jonghwa Lee <jonghwa3.lee@...sung.com>,
	MyungJoo Ham <myungjoo.ham@...sung.com>
Subject: [RESEND PATCH] [CPUFREQ] EXYNOS: bugfix on retrieving old_index from
 freqs.old

From: Jonghwa Lee <jonghwa3.lee@...sung.com>

The policy might have been changed since last call of target().
Thus, using cpufreq_frequency_table_target(), which depends on
policy to find the corresponding index from a frequency, may return
inconsistent index for freqs.old. Thus, old_index should be
calculated not based on the current policy.

We have been observing such issue when scaling_min/max_freq were
updated and sometimes cuased system lockups deu to incorrectly
configured voltages.

Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
---
 drivers/cpufreq/exynos-cpufreq.c |   14 ++++++++++++--
 1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/exynos-cpufreq.c b/drivers/cpufreq/exynos-cpufreq.c
index b243a7e..af2d81e 100644
--- a/drivers/cpufreq/exynos-cpufreq.c
+++ b/drivers/cpufreq/exynos-cpufreq.c
@@ -62,8 +62,18 @@ static int exynos_target(struct cpufreq_policy *policy,
 		goto out;
 	}
 
-	if (cpufreq_frequency_table_target(policy, freq_table,
-					   freqs.old, relation, &old_index)) {
+	/*
+	 * The policy max have been changed so that we cannot get proper
+	 * old_index with cpufreq_frequency_table_target(). Thus, ignore
+	 * policy and get the index from the raw freqeuncy table.
+	 */
+	for (old_index = 0;
+		freq_table[old_index].frequency != CPUFREQ_TABLE_END;
+		old_index++)
+		if (freq_table[old_index].frequency == freqs.old)
+			break;
+
+	if (freq_table[old_index].frequency == CPUFREQ_TABLE_END) {
 		ret = -EINVAL;
 		goto out;
 	}
-- 
1.7.4.1

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