linux-kernel - [PATCH 3/7] cpufreq: Only query drivers that implement cpufreq

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Message-Id: <1360088646-19104-4-git-send-email-dirk.brandewie@gmail.com>
Date:	Tue,  5 Feb 2013 10:24:02 -0800
From:	dirk.brandewie@...il.com
To:	linux-kernel@...r.kernel.org, cpufreq@...r.kernel.org
Cc:	Dirk Brandewie <dirk.brandewie@...il.com>,
	Dirk Brandewie <dirk.j.brandewie@...el.com>
Subject: [PATCH 3/7] cpufreq: Only query drivers that implement cpufreq_driver.target()

From: Dirk Brandewie <dirk.brandewie@...il.com>

Scaling drivers that implement cpufreq_driver.setpolicy() have
internal governors and may/will change the current operating frequency
very frequently this will cause cpufreq_out_of_sync() to be called
every time. Only call cpufreq_driver.get() for drivers that implement
cpufreq_driver.target()

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@...el.com>
---
 drivers/cpufreq/cpufreq.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 96bc302..d8daa4b 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1787,7 +1787,7 @@ int cpufreq_update_policy(unsigned int cpu)
 
 	/* BIOS might change freq behind our back
 	  -> ask driver for current freq and notify governors about a change */
-	if (cpufreq_driver->get) {
+	if (cpufreq_driver->get && cpufreq_driver->target) {
 		policy.cur = cpufreq_driver->get(cpu);
 		if (!data->cur) {
 			pr_debug("Driver did not initialize current freq");
-- 
1.7.7.6

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