linux-kernel - [PATCH 01/34] cpufreq: move freq change notifications to cpufreq core

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Date:	Fri, 16 Aug 2013 07:54:58 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	rjw@...k.pl
Cc:	linaro-kernel@...ts.linaro.org, patches@...aro.org,
	cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Andrew Lunn <andrew@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	Eric Miao <eric.y.miao@...il.com>,
	Hans-Christian Egtvedt <egtvedt@...fundet.no>,
	Jesper Nilsson <jesper.nilsson@...s.com>,
	John Crispin <blogic@...nwrt.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-cris-kernel@...s.com, Mikael Starvik <starvik@...s.com>,
	Russell King <linux@....linux.org.uk>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Sekhar Nori <nsekhar@...com>, Shawn Guo <shawn.guo@...aro.org>,
	sparclinux@...r.kernel.org, spear-devel@...t.st.com,
	Stephen Warren <swarren@...dia.com>,
	Steven Miao <realmz6@...il.com>,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH 01/34] cpufreq: move freq change notifications to cpufreq core

Most of the drivers do following in their ->target_index() routines:

	struct cpufreq_freqs freqs;
	freqs.old = old freq...
	freqs.new = new freq...

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

	/* Change rate here */

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);

This is replicated over all cpufreq drivers today and there doesn't exists a
good enough reason why this shouldn't be moved to cpufreq core instead.

There are few special cases though, like exynos5440, which doesn't do everything
on the call to ->target_index() routine and call some kind of bottom halves for
doing this work, work/tasklet/etc..

They may continue doing notification from their own code and so this patch
introduces another flag: CPUFREQ_NO_NOTIFICATION, which will be set by such
drivers.

Cc: Andrew Lunn <andrew@...n.ch>
Cc: David S. Miller <davem@...emloft.net>
Cc: Dmitry Eremin-Solenikov <dbaryshkov@...il.com>
Cc: Eric Miao <eric.y.miao@...il.com>
Cc: Hans-Christian Egtvedt <egtvedt@...fundet.no>
Cc: Jesper Nilsson <jesper.nilsson@...s.com>
Cc: John Crispin <blogic@...nwrt.org>
Cc: Kukjin Kim <kgene.kim@...sung.com>
Cc: Linus Walleij <linus.walleij@...aro.org>
Cc: linux-cris-kernel@...s.com
Cc: Mikael Starvik <starvik@...s.com>
Cc: Russell King <linux@....linux.org.uk>
Cc: Santosh Shilimkar <santosh.shilimkar@...com>
Cc: Sekhar Nori <nsekhar@...com>
Cc: Shawn Guo <shawn.guo@...aro.org>
Cc: sparclinux@...r.kernel.org
Cc: spear-devel@...t.st.com
Cc: Stephen Warren <swarren@...dia.com>
Cc: Steven Miao <realmz6@...il.com>
Cc: Tony Luck <tony.luck@...el.com>
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
 drivers/cpufreq/cpufreq.c | 34 ++++++++++++++++++++++++++++++++++
 include/linux/cpufreq.h   |  6 ++++++
 2 files changed, 40 insertions(+)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a7a1d3e..2782949 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1673,6 +1673,9 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 		retval = cpufreq_driver->target(policy, target_freq, relation);
 	else if (cpufreq_driver->target_index) {
 		struct cpufreq_frequency_table *freq_table;
+		struct cpufreq_freqs freqs;
+		unsigned long flags;
+		bool notify;
 		int index;
 
 		freq_table = cpufreq_frequency_get_table(policy->cpu);
@@ -1691,7 +1694,38 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
 		if (freq_table[index].frequency == policy->cur)
 			return 0;
 
+		read_lock_irqsave(&cpufreq_driver_lock, flags);
+		notify = !(cpufreq_driver->flags | CPUFREQ_NO_NOTIFICATION);
+		read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+		if (notify) {
+			freqs.old = policy->cur;
+			freqs.new = freq_table[index].frequency;
+
+			pr_debug("%s: cpu: %d, oldfreq: %u, new freq: %u\n",
+					__func__, policy->cpu, freqs.old,
+					freqs.new);
+
+			cpufreq_notify_transition(policy, &freqs,
+					CPUFREQ_PRECHANGE);
+		}
+
 		retval = cpufreq_driver->target_index(policy, index);
+		if (retval)
+			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);
+		}
 	}
 
 	return retval;
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index ff9c8df..62ce478 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -221,6 +221,12 @@ struct cpufreq_driver {
 					 * frequency transitions */
 #define CPUFREQ_PM_NO_WARN	0x04	/* don't warn on suspend/resume speed
 					 * mismatches */
+/*
+ * Driver will call cpufreq_notify_transition() in its target_index() routine
+ * and so cpufreq core must not call it. Only useful for drivers that implement
+ * target_index(), unused otherwise.
+ */
+#define CPUFREQ_NO_NOTIFICATION	0x08
 
 int cpufreq_register_driver(struct cpufreq_driver *driver_data);
 int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
-- 
1.7.12.rc2.18.g61b472e

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