Re: [PATCH] media: sunxi: sun6i_mipi_csi2.c/sun8i_a83t_mipi_csi2.c: clarify error handling

[Paul Kocialkowski <paul.kocialkowski@bootlin.com>]

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Hi Hans,

On Mon 18 Jul 22, 18:08, Hans Verkuil wrote:
> Both sun6i_mipi_csi2.c and sun8i_a83t_mipi_csi2.c have the same issue:
> the comment before the ret = 0 assignment is incorrect, drop it and
> always assign the result of the v4l2_subdev_call(..., 0) to ret.

Not sure what is incorrect about it. I agree that it's good to return the
return code of v4l2_subdev_call instead of always 0 on the !on path though.

> In the disable label check for !on and set ret to 0 in that case.
> 
> This fixes two smatch warnings:
> 
> drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c:193 sun6i_mipi_csi2_s_stream() warn: missing error code 'ret'

I don't think this is legit: the initialization of ret is specifically there
to avoid an undefined ret there.

> drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c:225 sun8i_a83t_mipi_csi2_s_stream() warn: missing error code 'ret'
> 
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> ---
>  .../media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c | 7 ++++---
>  .../sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c      | 7 ++++---
>  2 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c b/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c
> index 31e12f1506cb..a4e3f9a6b2ff 100644
> --- a/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c
> +++ b/drivers/media/platform/sunxi/sun6i-mipi-csi2/sun6i_mipi_csi2.c
> @@ -182,14 +182,13 @@ static int sun6i_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	unsigned int lanes_count =
>  		csi2_dev->bridge.endpoint.bus.mipi_csi2.num_data_lanes;
>  	unsigned long pixel_rate;
> -	/* Initialize to 0 to use both in disable label (ret != 0) and off. */
> -	int ret = 0;
> +	int ret;
>  
>  	if (!source_subdev)
>  		return -ENODEV;
>  
>  	if (!on) {
> -		v4l2_subdev_call(source_subdev, video, s_stream, 0);
> +		ret = v4l2_subdev_call(source_subdev, video, s_stream, 0);
>  		goto disable;
>  	}
>  
> @@ -281,6 +280,8 @@ static int sun6i_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	return 0;
>  
>  disable:
> +	if (!on)
> +		ret = 0;

Then this will always overwrite the ret value from v4l2_subdev_call with the
!on disable path. Looks like this can be removed.

What do you think?

Paul

>  	phy_power_off(dphy);
>  	sun6i_mipi_csi2_disable(csi2_dev);
>  
> diff --git a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
> index c82ede3ca0ff..d052ee77ef0a 100644
> --- a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
> +++ b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.c
> @@ -214,14 +214,13 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	unsigned int lanes_count =
>  		csi2_dev->bridge.endpoint.bus.mipi_csi2.num_data_lanes;
>  	unsigned long pixel_rate;
> -	/* Initialize to 0 to use both in disable label (ret != 0) and off. */
> -	int ret = 0;
> +	int ret;
>  
>  	if (!source_subdev)
>  		return -ENODEV;
>  
>  	if (!on) {
> -		v4l2_subdev_call(source_subdev, video, s_stream, 0);
> +		ret = v4l2_subdev_call(source_subdev, video, s_stream, 0);
>  		goto disable;
>  	}
>  
> @@ -313,6 +312,8 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	return 0;
>  
>  disable:
> +	if (!on)
> +		ret = 0;
>  	phy_power_off(dphy);
>  	sun8i_a83t_mipi_csi2_disable(csi2_dev);
>  
> -- 
> 2.35.1
> 

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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