From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manjunatha GK Subject: [PATCH v2] OMAP3 : Fix I2C lockup during timeout/error cases Date: Fri, 11 Dec 2009 11:09:08 +0530 Message-ID: <1260509948-12774-1-git-send-email-manjugk@ti.com> Return-path: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org Cc: Manjunatha GK , Nishanth Menon , "Sonasath, Moiz" , "Krishnamoorthy, Balaji T" , "Varadarajan, Charu Latha" , "George, Harith" List-Id: linux-i2c@vger.kernel.org Current OMAP3 I2C driver code does not follow the correct sequence for soft reset. Due to this, lock up issues are reported during timeout/error cases. This patch fixes above issue by disabling I2C controller as per OMAP3430 TRM for soft reset. As per TRM, I2C controller needs to be disabled as a first step during soft reset. Here is correct soft reset sequence: a. Ensure that the module is disabled (clear the I2Ci.I2C_CON[15] I2C_EN bit to 0). b. Set the I2Ci.I2C_SYSC[1] SRST bit to 1. c. Enable the module by setting I2Ci.I2C_CON[15] I2C_EN bit to 1. d. Check the I2Ci.I2C_SYSS[0] RDONE bit until it is set to 1 to indicate the software reset is complete. Tested on Zoom2, Zoom3, 3430SDP and 3630SDP Signed-off-by: Manjunatha GK Signed-off-by: George, Harith Acked-by: Varadarajan, Charu Latha --- v1 : Initital version v2 : Removed delay since time taken for disabling I2C controller is zero jiffies drivers/i2c/busses/i2c-omap.c | 5 +++++ 1 files changed, 5 insertions(+), 0 deletions(-) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index 827da08..74620c0 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -265,6 +265,11 @@ static int omap_i2c_init(struct omap_i2c_dev *dev) unsigned long internal_clk = 0; if (dev->rev >= OMAP_I2C_REV_2) { + /* Disable I2C controller before soft reset */ + omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, + omap_i2c_read_reg(dev, OMAP_I2C_CON_REG) & + ~(OMAP_I2C_CON_EN)); + omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, SYSC_SOFTRESET_MASK); /* For some reason we need to set the EN bit before the * reset done bit gets set. */ -- 1.6.0.4