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[v1,1/2] i2c: imx: fix i2c issue when reading multiple messages

Message ID 20260218150940.131354-2-eichest@gmail.com
State Accepted
Delegated to: Andi Shyti
Headers show
Series i2c: imx: fix i2c issues when reading messages | expand

Commit Message

Stefan Eichenberger Feb. 18, 2026, 3:08 p.m. UTC 
From: Stefan Eichenberger <stefan.eichenberger@toradex.com>

When reading multiple messages, meaning a repeated start is required,
polling the bus busy bit must be avoided. This must only be done for
the last message. Otherwise, the driver will timeout.

Here an example of such a sequence that fails with an error:
i2ctransfer -y -a 0 w1@0x00 0x02 r1 w1@0x00 0x02 r1
Error: Sending messages failed: Connection timed out

Fixes: 5f5c2d4579ca ("i2c: imx: prevent rescheduling in non dma mode")
Cc: <stable@vger.kernel.org> # v6.13+
Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
---
 drivers/i2c/busses/i2c-imx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Frank Li Feb. 18, 2026, 4:22 p.m. UTC | #1 
On Wed, Feb 18, 2026 at 04:08:49PM +0100, Stefan Eichenberger wrote:
> From: Stefan Eichenberger <stefan.eichenberger@toradex.com>
>
> When reading multiple messages, meaning a repeated start is required,
> polling the bus busy bit must be avoided. This must only be done for
> the last message. Otherwise, the driver will timeout.
>
> Here an example of such a sequence that fails with an error:
> i2ctransfer -y -a 0 w1@0x00 0x02 r1 w1@0x00 0x02 r1
> Error: Sending messages failed: Connection timed out
>
> Fixes: 5f5c2d4579ca ("i2c: imx: prevent rescheduling in non dma mode")
> Cc: <stable@vger.kernel.org> # v6.13+
> Signed-off-by: Stefan Eichenberger <stefan.eichenberger@toradex.com>
> ---
Reviewed-by: Frank Li <Frank.Li@nxp.com>
>  drivers/i2c/busses/i2c-imx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 85f554044cf1e..56e2a14495a9a 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -1522,7 +1522,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
>  		dev_err(&i2c_imx->adapter.dev, "<%s> read timedout\n", __func__);
>  		return -ETIMEDOUT;
>  	}
> -	if (!i2c_imx->stopped)
> +	if (i2c_imx->is_lastmsg && !i2c_imx->stopped)
>  		return i2c_imx_bus_busy(i2c_imx, 0, false);
>
>  	return 0;
> --
> 2.51.0
>
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Patch

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 85f554044cf1e..56e2a14495a9a 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -1522,7 +1522,7 @@  static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
 		dev_err(&i2c_imx->adapter.dev, "<%s> read timedout\n", __func__);
 		return -ETIMEDOUT;
 	}
-	if (!i2c_imx->stopped)
+	if (i2c_imx->is_lastmsg && !i2c_imx->stopped)
 		return i2c_imx_bus_busy(i2c_imx, 0, false);
 
 	return 0;