linux-kernel - [PATCH v4] i2c: s3c2410: dont need CPU

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Date:	Tue, 26 Nov 2013 09:52:46 +0530
From:	Naveen Krishna Chatradhi <ch.naveen@...sung.com>
To:	linux-i2c@...r.kernel.org
Cc:	sjg@...omium.org, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org, wsa@...-dreams.de,
	ben-linux@...ff.org, grant.likely@...retlab.ca, broonie@...nel.org,
	dianders@...omium.org, cpgs@...sung.com, t.figa@...sung.com
Subject: [PATCH v4] i2c: s3c2410: dont need CPU_FREQ transitions for exynos
 series

For Exynos4 and Exynos5 SoCs from Samsung the i2c clock is based
on a fixed 66 MHz peripheral clock, and therefore is completely
independent of the cpu frequency.
Thus, registering for a CPU freq notifier is very wasteful.

This patch modifes the code such that, i2c bus registers to
cpu_freq_transition only if CONFIG_CPU_FREQ_S3C24XX is enabled.

This change should save a bunch of cpufreq transitions calls
which does not apply to exynos SoCs.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@...sung.com>
Acked-by: Kyungmin Park <kyungmin.park@...sung.com>
Reviewed-by: Doug Anderson <dianders@...omium.org>
---
Changes since v3:
As per discussion at https://patchwork.kernel.org/patch/3235091/
Post f023f8dd59 commit we should be using
ARM_S3C24XX_CPUFREQ instead of CPU_FREQ_S3C24XX

upstrea linux kernel and linuxsamsung already has the commit
f023f8dd59. Hence, rebasing the patch.

 drivers/i2c/busses/i2c-s3c2410.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index bf8fb94..a77ce13 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -123,7 +123,7 @@ struct s3c24xx_i2c {
 	struct s3c2410_platform_i2c	*pdata;
 	int			gpios[2];
 	struct pinctrl          *pctrl;
-#ifdef CONFIG_CPU_FREQ
+#if defined(CONFIG_ARM_S3C24XX_CPUFREQ)
 	struct notifier_block	freq_transition;
 #endif
 };
@@ -843,7 +843,7 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
 	return 0;
 }
 
-#ifdef CONFIG_CPU_FREQ
+#if defined(CONFIG_ARM_S3C24XX_CPUFREQ)
 
 #define freq_to_i2c(_n) container_of(_n, struct s3c24xx_i2c, freq_transition)
 
-- 
1.7.10.4

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