linux-kernel - [PATCH] rtc: twl: optimize IRQ bit access

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Message-Id: <1326973942-11576-1-git-send-email-vbyravarasu@nvidia.com>
Date:	Thu, 19 Jan 2012 17:22:22 +0530
From:	Venu Byravarasu <vbyravarasu@...dia.com>
To:	a.zummo@...ertech.it, rtc-linux@...glegroups.com,
	linux-kernel@...r.kernel.org
Cc:	Venu Byravarasu <vbyravarasu@...dia.com>
Subject: [PATCH] rtc: twl: optimize IRQ bit access

From: Venu Byravarasu <vbyravarasu@...dia.com>

As TWL RTC driver is having a cached copy of enabled RTC interrupt bits
in variable rtc_irq_bits, that can be checked before really setting
or masking any of the interrupt bits.

Signed-off-by: Venu Byravarasu <vbyravarasu@...dia.com>
---
 drivers/rtc/rtc-twl.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/rtc/rtc-twl.c b/drivers/rtc/rtc-twl.c
index a0236a0..b1f6c8b 100644
--- a/drivers/rtc/rtc-twl.c
+++ b/drivers/rtc/rtc-twl.c
@@ -176,6 +176,10 @@ static int set_rtc_irq_bit(unsigned char bit)
 	unsigned char val;
 	int ret;
 
+	/* if the bit is set, return from here */
+	if (rtc_irq_bits & bit)
+		return 0;
+
 	val = rtc_irq_bits | bit;
 	val &= ~BIT_RTC_INTERRUPTS_REG_EVERY_M;
 	ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
@@ -193,6 +197,10 @@ static int mask_rtc_irq_bit(unsigned char bit)
 	unsigned char val;
 	int ret;
 
+	/* if the bit is clear, return from here */
+	if (!(rtc_irq_bits & bit))
+		return 0;
+
 	val = rtc_irq_bits & ~bit;
 	ret = twl_rtc_write_u8(val, REG_RTC_INTERRUPTS_REG);
 	if (ret == 0)
-- 
1.7.1.1

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