Re: [PATCH v3 2/2] media: i2c: vd55g1: stop streaming after an exposure read error

[Benjamin Mugnier <benjamin.mugnier@foss.st.com>]

Hi,

Le 13/10/2026 à 05:10, Jizhou Tong a écrit :
> Stream-off saves exposure settings for the next automatic-exposure cold
> start. If that read fails, its error is passed to the subsequent CCI
> operations, which skip accesses when the error accumulator is nonzero.
> The sensor stop command is therefore never issued, although the runtime
> PM reference is released.
> 
> Log the exposure snapshot failure separately and clear the accumulator
> before stopping the sensor. Treat the optional snapshot failure as a
> warning: a successful stop returns success, while a stop failure is
> returned to the caller. Completing stream shutdown takes precedence
> over saving exposure settings for the next start.
> 
> Signed-off-by: Jizhou Tong <fqwqf@fqwqf.xyz>

Reviewed-By: Benjamin Mugnier <benjamin.mugnier@foss.st.com>

> ---
> Changes in v3: reference the CCI error-accumulator API in the
> stream-off comment. No functional changes from v2.
> 
> Fault-injection harness:
> https://gist.github.com/fQwQf/60bd12627e06b10a2fc159e545f85dae/7b21a7d3a1b676a0e4cdaba06168ede09a2949e3
> 
>  drivers/media/i2c/vd55g1.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/media/i2c/vd55g1.c b/drivers/media/i2c/vd55g1.c
> index 78e4aebfdd3b24b867ea4d077dc1b676c4a595da..e78835f014e65bfc2b3dcc2aaee7b054fb5da390 100644
> --- a/drivers/media/i2c/vd55g1.c
> +++ b/drivers/media/i2c/vd55g1.c
> @@ -1190,6 +1190,14 @@ static int vd55g1_disable_streams(struct v4l2_subdev *sd,
>  
>  	/* Retrieve Expo cluster to enable coldstart of AE */
>  	ret = vd55g1_read_expo_cluster(sensor);
> +	if (ret)
> +		dev_warn(sensor->dev, "Failed to save exposure: %d\n", ret);
> +
> +	/*
> +	 * cci_write() skips writes when its error accumulator is set
> +	 * (see include/media/v4l2-cci.h). Start a separate stop sequence.
> +	 */
> +	ret = 0;
>  
>  	vd55g1_write(sensor, VD55G1_REG_STREAMING, VD55G1_STREAMING_STOP_STREAM,
>  		     &ret);

-- 
Regards,
Benjamin