linux-kernel - [PATCH 1/4] i2c: designware: No need to disable already disabled controller

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Message-Id: <1400164644-3222-2-git-send-email-mika.westerberg@linux.intel.com>
Date:	Thu, 15 May 2014 17:37:21 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Wolfram Sang <wsa@...-dreams.de>
Cc:	Yao Jin <yao.jin@...el.com>, Aubrey Li <aubrey.li@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] i2c: designware: No need to disable already disabled controller

If the controller is already in desired state (enabled/disabled) there is
no point in setting its state again.

Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/i2c/busses/i2c-designware-core.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index b58ecf19e767..b0792675b970 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -258,6 +258,10 @@ static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool enable)
 {
 	int timeout = 100;
 
+	/* In case the controller is already in desired state */
+	if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == enable)
+		return;
+
 	do {
 		dw_writel(dev, enable, DW_IC_ENABLE);
 		if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == enable)
-- 
2.0.0.rc2

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