From: Ye Li ye.li@nxp.com
In xfer function, both bus_i2c_read and bus_i2c_write will send a STOP command. This causes a problem when reading register data from i2c device.
Generally two operations comprise the register data reading: 1. Write the register address to i2c device. START | chip_addr | W | ACK | register_addr | ACK |
2. Read the Data from i2c device. START | chip_addr | R | ACK | DATA | NACK | STOP
The STOP command should happen at the end of the transfer, otherwise we will always get data from register address 0
Signed-off-by: Ye Li ye.li@nxp.com Acked-by: Peng Fan peng.fan@nxp.com Reviewed-by: Heiko Schocher hs@denx.de ---
V2: Add review tag
drivers/i2c/imx_lpi2c.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/i2c/imx_lpi2c.c b/drivers/i2c/imx_lpi2c.c index d2e11b411b..585787a35c 100644 --- a/drivers/i2c/imx_lpi2c.c +++ b/drivers/i2c/imx_lpi2c.c @@ -225,9 +225,6 @@ static int bus_i2c_read(struct imx_lpi2c_reg *regs, u32 chip, u8 *buf, int len) if (result) return result; result = bus_i2c_receive(regs, buf, len); - if (result) - return result; - result = bus_i2c_stop(regs); if (result) return result;
@@ -242,9 +239,6 @@ static int bus_i2c_write(struct imx_lpi2c_reg *regs, u32 chip, u8 *buf, int len) if (result) return result; result = bus_i2c_send(regs, buf, len); - if (result) - return result; - result = bus_i2c_stop(regs); if (result) return result;
@@ -380,7 +374,7 @@ static int imx_lpi2c_probe_chip(struct udevice *bus, u32 chip, static int imx_lpi2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs) { struct imx_lpi2c_reg *regs; - int ret = 0; + int ret = 0, ret_stop;
regs = (struct imx_lpi2c_reg *)devfdt_get_addr(bus); for (; nmsgs > 0; nmsgs--, msg++) { @@ -398,6 +392,12 @@ static int imx_lpi2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs) if (ret) debug("i2c_write: error sending\n");
+ ret_stop = bus_i2c_stop(regs); + if (ret_stop) + debug("i2c_xfer: stop bus error\n"); + + ret |= ret_stop; + return ret; }