| Message ID | 20180528122526.20597-26-peng.fan@nxp.com |
|---|---|
| State | Superseded |
| Delegated to: | Stefano Babic |
| Headers | show |
| Series | imx: add i.MX8QXP support | expand |
Hello Peng, Am 28.05.2018 um 14:25 schrieb Peng Fan: > 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> > Cc: Heiko Schocher <hs@denx.de> > --- > drivers/i2c/imx_lpi2c.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) Good catch. Reviewed-by: Heiko Schocher <hs@denx.de> bye, Heiko
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; }