Subject: Re: [PATCH 04/16] media: sun8i-a83t-mipi-csi2: Use V4L2 subdev active state

From: Paul Kocialkowski <[email-masked]>
Date: Mon, 18 May 2026 16:09:41 +0200

Le Mon 18 May 26, 12:24, Paul Kocialkowski a écrit :
> From: Arash Golgol <[email-masked]>
> 
> Use the V4L2 subdev active state API to store the active format.
> This simplifies the driver not only by dropping the bridge mbus_format
> field, but it also allows dropping the bridge lock, replaced with
> the state lock.
> 
> The sun8i-a83t-mipi-csi2 hardware does not perform any format
> conversion. Enforce identical formats on the sink and source pads in
> the set_fmt() and init_state() callbacks.
> 
> Signed-off-by: Arash Golgol <[email-masked]>

I forgot to pick it up but this is already:

Reviewed-by: Paul Kocialkowski <[email-masked]>
Tested-by: Paul Kocialkowski <[email-masked]>

Paul

> ---
>  .../sun8i_a83t_mipi_csi2.c                    | 113 +++++++++---------
>  .../sun8i_a83t_mipi_csi2.h                    |   2 -
>  2 files changed, 56 insertions(+), 59 deletions(-)
> 
> 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 dbc51daa4fe3..2b7635f3952d 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
> @@ -144,12 +144,12 @@ sun8i_a83t_mipi_csi2_disable(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
>  }
>  
>  static void
> -sun8i_a83t_mipi_csi2_configure(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
> +sun8i_a83t_mipi_csi2_configure(struct sun8i_a83t_mipi_csi2_device *csi2_dev,
> +			       const struct v4l2_mbus_framefmt *mbus_format)
>  {
>  	struct regmap *regmap = csi2_dev->regmap;
>  	unsigned int lanes_count =
>  		csi2_dev->bridge.endpoint.bus.mipi_csi2.num_data_lanes;
> -	struct v4l2_mbus_framefmt *mbus_format = &csi2_dev->bridge.mbus_format;
>  	const struct sun8i_a83t_mipi_csi2_format *format;
>  	struct device *dev = csi2_dev->dev;
>  	u32 version = 0;
> @@ -205,7 +205,8 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	struct v4l2_subdev *source_subdev = csi2_dev->bridge.source_subdev;
>  	union phy_configure_opts dphy_opts = { 0 };
>  	struct phy_configure_opts_mipi_dphy *dphy_cfg = &dphy_opts.mipi_dphy;
> -	struct v4l2_mbus_framefmt *mbus_format = &csi2_dev->bridge.mbus_format;
> +	struct v4l2_subdev_state *state;
> +	const struct v4l2_mbus_framefmt *mbus_format;
>  	const struct sun8i_a83t_mipi_csi2_format *format;
>  	struct phy *dphy = csi2_dev->dphy;
>  	struct device *dev = csi2_dev->dev;
> @@ -215,8 +216,12 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	unsigned long pixel_rate;
>  	int ret;
>  
> -	if (!source_subdev)
> -		return -ENODEV;
> +	state = v4l2_subdev_lock_and_get_active_state(subdev);
> +
> +	if (!source_subdev) {
> +		ret = -ENODEV;
> +		goto unlock;
> +	}
>  
>  	if (!on) {
>  		v4l2_subdev_call(source_subdev, video, s_stream, 0);
> @@ -228,7 +233,7 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  
>  	ret = pm_runtime_resume_and_get(dev);
>  	if (ret < 0)
> -		return ret;
> +		goto unlock;
>  
>  	/* Sensor pixel rate */
>  
> @@ -254,6 +259,9 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  		goto error_pm;
>  	}
>  
> +	mbus_format =
> +		v4l2_subdev_state_get_format(state,
> +					     SUN8I_A83T_MIPI_CSI2_PAD_SINK);
>  	format = sun8i_a83t_mipi_csi2_format_find(mbus_format->code);
>  	if (WARN_ON(!format)) {
>  		ret = -ENODEV;
> @@ -292,7 +300,7 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  
>  	/* Controller */
>  
> -	sun8i_a83t_mipi_csi2_configure(csi2_dev);
> +	sun8i_a83t_mipi_csi2_configure(csi2_dev, mbus_format);
>  	sun8i_a83t_mipi_csi2_enable(csi2_dev);
>  
>  	/* D-PHY */
> @@ -309,7 +317,8 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  	if (ret && ret != -ENOIOCTLCMD)
>  		goto disable;
>  
> -	return 0;
> +	ret = 0;
> +	goto unlock;
>  
>  disable:
>  	phy_power_off(dphy);
> @@ -318,6 +327,8 @@ static int sun8i_a83t_mipi_csi2_s_stream(struct v4l2_subdev *subdev, int on)
>  error_pm:
>  	pm_runtime_put(dev);
>  
> +unlock:
> +	v4l2_subdev_unlock_state(state);
>  	return ret;
>  }
>  
> @@ -341,22 +352,24 @@ sun8i_a83t_mipi_csi2_mbus_format_prepare(struct v4l2_mbus_framefmt *mbus_format)
>  static int sun8i_a83t_mipi_csi2_init_state(struct v4l2_subdev *subdev,
>  					   struct v4l2_subdev_state *state)
>  {
> -	struct sun8i_a83t_mipi_csi2_device *csi2_dev =
> -		v4l2_get_subdevdata(subdev);
> -	unsigned int pad = SUN8I_A83T_MIPI_CSI2_PAD_SINK;
> -	struct v4l2_mbus_framefmt *mbus_format =
> -		v4l2_subdev_state_get_format(state, pad);
> -	struct mutex *lock = &csi2_dev->bridge.lock;
> +	unsigned int pad;
>  
> -	mutex_lock(lock);
> +	/*
> +	 * This subdev does not perform format conversion,
> +	 * initialize both pads identically.
> +	 */
> +	for (pad = 0; pad < subdev->entity.num_pads; pad++) {
> +		struct v4l2_mbus_framefmt *mbus_format;
>  
> -	mbus_format->code = sun8i_a83t_mipi_csi2_formats[0].mbus_code;
> -	mbus_format->width = 640;
> -	mbus_format->height = 480;
> +		mbus_format = v4l2_subdev_state_get_format(state, pad);
> +
> +		mbus_format->code = sun8i_a83t_mipi_csi2_formats[0].mbus_code;
> +		mbus_format->width = 640;
> +		mbus_format->height = 480;
>  
> -	sun8i_a83t_mipi_csi2_mbus_format_prepare(mbus_format);
> +		sun8i_a83t_mipi_csi2_mbus_format_prepare(mbus_format);
> +	}
>  
> -	mutex_unlock(lock);
>  
>  	return 0;
>  }
> @@ -375,55 +388,33 @@ sun8i_a83t_mipi_csi2_enum_mbus_code(struct v4l2_subdev *subdev,
>  	return 0;
>  }
>  
> -static int sun8i_a83t_mipi_csi2_get_fmt(struct v4l2_subdev *subdev,
> -					struct v4l2_subdev_state *state,
> -					struct v4l2_subdev_format *format)
> -{
> -	struct sun8i_a83t_mipi_csi2_device *csi2_dev =
> -		v4l2_get_subdevdata(subdev);
> -	struct v4l2_mbus_framefmt *mbus_format = &format->format;
> -	struct mutex *lock = &csi2_dev->bridge.lock;
> -
> -	mutex_lock(lock);
> -
> -	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
> -		*mbus_format = *v4l2_subdev_state_get_format(state,
> -							     format->pad);
> -	else
> -		*mbus_format = csi2_dev->bridge.mbus_format;
> -
> -	mutex_unlock(lock);
> -
> -	return 0;
> -}
> -
>  static int sun8i_a83t_mipi_csi2_set_fmt(struct v4l2_subdev *subdev,
>  					struct v4l2_subdev_state *state,
>  					struct v4l2_subdev_format *format)
>  {
> -	struct sun8i_a83t_mipi_csi2_device *csi2_dev =
> -		v4l2_get_subdevdata(subdev);
> -	struct v4l2_mbus_framefmt *mbus_format = &format->format;
> -	struct mutex *lock = &csi2_dev->bridge.lock;
> +	struct v4l2_mbus_framefmt *fmt;
>  
> -	mutex_lock(lock);
> +	/* The format on the source pad always matches the sink pad. */
> +	if (format->pad != SUN8I_A83T_MIPI_CSI2_PAD_SINK)
> +		return v4l2_subdev_get_fmt(subdev, state, format);
>  
> -	sun8i_a83t_mipi_csi2_mbus_format_prepare(mbus_format);
> +	sun8i_a83t_mipi_csi2_mbus_format_prepare(&format->format);
>  
> -	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
> -		*v4l2_subdev_state_get_format(state, format->pad) =
> -			*mbus_format;
> -	else
> -		csi2_dev->bridge.mbus_format = *mbus_format;
> +	/* Set the format on the sink pad. */
> +	fmt = v4l2_subdev_state_get_format(state, format->pad);
> +	*fmt = format->format;
>  
> -	mutex_unlock(lock);
> +	/* Propagate the format to the source pad. */
> +	fmt = v4l2_subdev_state_get_format(state,
> +					   SUN8I_A83T_MIPI_CSI2_PAD_SOURCE);
> +	*fmt = format->format;
>  
>  	return 0;
>  }
>  
>  static const struct v4l2_subdev_pad_ops sun8i_a83t_mipi_csi2_pad_ops = {
>  	.enum_mbus_code	= sun8i_a83t_mipi_csi2_enum_mbus_code,
> -	.get_fmt	= sun8i_a83t_mipi_csi2_get_fmt,
> +	.get_fmt	= v4l2_subdev_get_fmt,
>  	.set_fmt	= sun8i_a83t_mipi_csi2_set_fmt,
>  };
>  
> @@ -540,8 +531,6 @@ sun8i_a83t_mipi_csi2_bridge_setup(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
>  	bool notifier_registered = false;
>  	int ret;
>  
> -	mutex_init(&bridge->lock);
> -
>  	/* V4L2 Subdev */
>  
>  	v4l2_subdev_init(subdev, &sun8i_a83t_mipi_csi2_subdev_ops);
> @@ -570,6 +559,12 @@ sun8i_a83t_mipi_csi2_bridge_setup(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
>  	if (ret)
>  		return ret;
>  
> +	/* V4L2 Subdev finalize */
> +
> +	ret = v4l2_subdev_init_finalize(subdev);
> +	if (ret < 0)
> +		goto error_media_entity_cleanup;
> +
>  	/* V4L2 Async */
>  
>  	v4l2_async_subdev_nf_init(notifier, subdev);
> @@ -603,6 +598,9 @@ sun8i_a83t_mipi_csi2_bridge_setup(struct sun8i_a83t_mipi_csi2_device *csi2_dev)
>  error_v4l2_notifier_cleanup:
>  	v4l2_async_nf_cleanup(notifier);
>  
> +	v4l2_subdev_cleanup(subdev);
> +
> +error_media_entity_cleanup:
>  	media_entity_cleanup(&subdev->entity);
>  
>  	return ret;
> @@ -617,6 +615,7 @@ sun8i_a83t_mipi_csi2_bridge_cleanup(struct sun8i_a83t_mipi_csi2_device *csi2_dev
>  	v4l2_async_unregister_subdev(subdev);
>  	v4l2_async_nf_unregister(notifier);
>  	v4l2_async_nf_cleanup(notifier);
> +	v4l2_subdev_cleanup(subdev);
>  	media_entity_cleanup(&subdev->entity);
>  }
>  
> diff --git a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h
> index f1e64c53434c..819527bcd64d 100644
> --- a/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h
> +++ b/drivers/media/platform/sunxi/sun8i-a83t-mipi-csi2/sun8i_a83t_mipi_csi2.h
> @@ -33,8 +33,6 @@ struct sun8i_a83t_mipi_csi2_bridge {
>  	struct media_pad		pads[SUN8I_A83T_MIPI_CSI2_PAD_COUNT];
>  	struct v4l2_fwnode_endpoint	endpoint;
>  	struct v4l2_async_notifier	notifier;
> -	struct v4l2_mbus_framefmt	mbus_format;
> -	struct mutex			lock; /* Mbus format lock. */
>  
>  	struct v4l2_subdev		*source_subdev;
>  };
> -- 
> 2.54.0
> 

-- 
Paul Kocialkowski,

Independent contractor - sys-base - https://www.sys-base.io/
Free software developer - https://www.paulk.fr/

Expert in multimedia, graphics and embedded hardware support with Linux.