diff mbox series

[2/3] i2c:imx: Add an extra read at the end of an I2C slave read

Message ID 20211005003216.2670632-3-minyard@acm.org
State Superseded
Headers show
Series i2c:imx: Deliver a timely stop on slave side, fix recv | expand

Commit Message

Corey Minyard Oct. 5, 2021, 12:32 a.m. UTC 
From: Corey Minyard <cminyard@mvista.com>

The I2C slave interface expects that the driver will read ahead one
byte.  The IMX driver/device doesn't do this, but simulate it so that
read operations get their index set correctly.

Signed-off-by: Corey Minyard <minyard@acm.org>
Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>
---
 drivers/i2c/busses/i2c-imx.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

Oleksij Rempel Nov. 10, 2021, 8:58 a.m. UTC | #1 
On Mon, Oct 04, 2021 at 07:32:15PM -0500, minyard@acm.org wrote:
> From: Corey Minyard <cminyard@mvista.com>
> 
> The I2C slave interface expects that the driver will read ahead one
> byte.  The IMX driver/device doesn't do this, but simulate it so that
> read operations get their index set correctly.
> 
> Signed-off-by: Corey Minyard <minyard@acm.org>
> Tested-by: Andrew Manley <andrew.manley@sealingtech.com>
> Reviewed-by: Andrew Manley <andrew.manley@sealingtech.com>

Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>

> ---
>  drivers/i2c/busses/i2c-imx.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 97369fe48b30..26a04dc0590b 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -769,6 +769,15 @@ static irqreturn_t i2c_imx_slave_handle(struct imx_i2c_struct *i2c_imx,
>  		ctl &= ~I2CR_MTX;
>  		imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
>  		imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> +
> +		/*
> +		 * The i2c slave interface requires one extra dummy
> +		 * read at the end to keep things in line.  See the
> +		 * I2C slave docs for details.
> +		 */
> +		i2c_imx_slave_event(i2c_imx,
> +				    I2C_SLAVE_READ_PROCESSED, &value);
> +
>  		i2c_imx_slave_finish_op(i2c_imx);
>  		return IRQ_HANDLED;
>  	}
> -- 
> 2.25.1
> 
>
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 97369fe48b30..26a04dc0590b 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -769,6 +769,15 @@  static irqreturn_t i2c_imx_slave_handle(struct imx_i2c_struct *i2c_imx,
 		ctl &= ~I2CR_MTX;
 		imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
 		imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+
+		/*
+		 * The i2c slave interface requires one extra dummy
+		 * read at the end to keep things in line.  See the
+		 * I2C slave docs for details.
+		 */
+		i2c_imx_slave_event(i2c_imx,
+				    I2C_SLAVE_READ_PROCESSED, &value);
+
 		i2c_imx_slave_finish_op(i2c_imx);
 		return IRQ_HANDLED;
 	}