From: Grygorii Strashko <grygorii.strashko@ti.com>
To: Wolfram Sang <wsa@the-dreams.de>, Tony Lindgren <tony@atomide.com>
Cc: <linux-kernel@vger.kernel.org>, <linux-omap@vger.kernel.org>,
<linux-i2c@vger.kernel.org>,
Grygorii Strashko <grygorii.strashko@ti.com>,
Kevin Hilman <khilman@linaro.org>, Felipe Balbi <balbi@ti.com>
Subject: [PATCH 4/5] i2c: omap: query STP always when NACK is received
Date: Fri, 7 Jun 2013 21:46:07 +0300 [thread overview]
Message-ID: <1370630768-4077-5-git-send-email-grygorii.strashko@ti.com> (raw)
In-Reply-To: <1370630768-4077-1-git-send-email-grygorii.strashko@ti.com>
According to I2C specification the NACK should be handled as folowing:
"When SDA remains HIGH during this ninth clock pulse, this is defined as the Not
Acknowledge signal. The master can then gene rate either a STOP condition to
abort the transfer, or a repeated START condition to start a new transfer."
[http://www.nxp.com/documents/user_manual/UM10204.pdf]
The same is recomened by TI I2C wiki:
http://processors.wiki.ti.com/index.php/I2C_Tips
Currently, the OMAP I2C driver interrupts I2C trunsfer in case of NACK, but
It queries Stop condition OMAP_I2C_CON_REG.STP=1 only if NACK has been received
during the last message transmitting/recieving.
This may lead to stuck Bus in "Bus Busy" until I2C IP reset (idle/enable).
Hence, fix it by querying Stop condition (STP) always when NACK is received.
CC: Kevin Hilman <khilman@linaro.org>
CC: Felipe Balbi <balbi@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
drivers/i2c/busses/i2c-omap.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
index 46fb8a5..b3daf3f 100644
--- a/drivers/i2c/busses/i2c-omap.c
+++ b/drivers/i2c/busses/i2c-omap.c
@@ -618,11 +618,10 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
if (dev->cmd_err & OMAP_I2C_STAT_NACK) {
if (msg->flags & I2C_M_IGNORE_NAK)
return 0;
- if (stop) {
- w = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
- w |= OMAP_I2C_CON_STP;
- omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
- }
+
+ w = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
+ w |= OMAP_I2C_CON_STP;
+ omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
return -EREMOTEIO;
}
return -EIO;
--
1.7.9.5
next prev parent reply other threads:[~2013-06-07 18:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-07 18:46 [PATCH 0/5] v3.10-rc4: fix OMAP4 boot failure if CONFIG_SENSORS_LM75=y Grygorii Strashko
2013-06-07 18:46 ` [PATCH 1/5] i2c: omap: fix spurious IRQs: disable/enable IRQ at INTC when idle Grygorii Strashko
2013-06-07 20:51 ` Kevin Hilman
2013-06-19 18:35 ` Grygorii Strashko
2013-06-19 19:31 ` Felipe Balbi
2013-06-19 20:01 ` Kevin Hilman
2013-06-19 20:56 ` Felipe Balbi
2013-06-07 18:46 ` [PATCH 2/5] i2c: omap: add runtime check in isr to be sure that i2c is enabled Grygorii Strashko
2013-06-07 19:02 ` Felipe Balbi
2013-06-19 18:42 ` Grygorii Strashko
2013-06-19 19:39 ` Felipe Balbi
2013-06-07 18:46 ` [PATCH 3/5] i2c: omap: handle all irqs befor unblocking omap_i2c_xfer_msg() Grygorii Strashko
2013-06-07 19:05 ` Felipe Balbi
2013-06-19 18:43 ` Grygorii Strashko
2013-06-19 19:44 ` Felipe Balbi
2013-06-07 18:46 ` Grygorii Strashko [this message]
2013-06-07 19:07 ` [PATCH 4/5] i2c: omap: query STP always when NACK is received Felipe Balbi
2013-06-07 18:46 ` [PATCH 5/5] i2c: omap: remove omap_i2c_isr() hw irq handler Grygorii Strashko
2013-06-07 19:07 ` Felipe Balbi
2013-06-19 18:43 ` Grygorii Strashko
2013-06-19 19:44 ` Felipe Balbi
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