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>

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>
Grygorii Strashko · Wolfram Sang · Eric Lee · Eric Lee · Eric Lee · Eric Lee
1 parent 869c6a3ede
Showing 1 changed file with 4 additions and 5 deletions Side-by-side Diff
drivers/i2c/busses/i2c-omap.c
@@ -615,11 +615,10 @@
 	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;
...	...	@@ -615,11 +615,10 @@
615	615	if (dev->cmd_err & OMAP_I2C_STAT_NACK) {
616	616	if (msg->flags & I2C_M_IGNORE_NAK)
617	617	return 0;
618		- if (stop) {
619		- w = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
620		- w \|= OMAP_I2C_CON_STP;
621		- omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
622		- }
	618	+
	619	+ w = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
	620	+ w \|= OMAP_I2C_CON_STP;
	621	+ omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
623	622	return -EREMOTEIO;
624	623	}
625	624	return -EIO;