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| author | Grygorii Strashko <grygorii.strashko@ti.com> | 2013-06-07 21:46:07 +0300 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2013-08-19 14:08:19 +0200 |
| commit | cda2109a26eb6fa58acfeae878eed87492480eae (patch) | |
| tree | 4dce2af0e318dd77b33f0c279d8be066def96409 /drivers/i2c/busses | |
| parent | 869c6a3ededbb108b03a11a7c9d4c8a4fb607063 (diff) | |
| download | lwn-cda2109a26eb6fa58acfeae878eed87492480eae.tar.gz lwn-cda2109a26eb6fa58acfeae878eed87492480eae.zip | |
i2c: omap: query STP always when NACK is received
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.
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Hein Tibosch <hein_tibosch@yahoo.es>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/busses')
| -rw-r--r-- | drivers/i2c/busses/i2c-omap.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index d09512e4f488..c6db76ec5a22 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -615,11 +615,10 @@ 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; |