Re: [PATCH 01/19] media: adv748x: Add support for active state

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jacopo,

Thank you for the patch.

On Tue, Apr 30, 2024 at 12:39:37PM +0200, Jacopo Mondi wrote:
> Initialize and use the subdev active state to store the subdevice
> format.
> 
> This simplifies the implementation of the get_fmt and set_fmt pad
> operations.
> 
> Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
> ---
>  drivers/media/i2c/adv748x/adv748x-csi2.c | 69 ++++--------------------
>  drivers/media/i2c/adv748x/adv748x.h      |  1 -
>  2 files changed, 11 insertions(+), 59 deletions(-)
> 
> diff --git a/drivers/media/i2c/adv748x/adv748x-csi2.c b/drivers/media/i2c/adv748x/adv748x-csi2.c
> index 5b265b722394..435b0909bbef 100644
> --- a/drivers/media/i2c/adv748x/adv748x-csi2.c
> +++ b/drivers/media/i2c/adv748x/adv748x-csi2.c
> @@ -139,78 +139,26 @@ static const struct v4l2_subdev_video_ops adv748x_csi2_video_ops = {
>   * But we must support setting the pad formats for format propagation.
>   */
>  
> -static struct v4l2_mbus_framefmt *
> -adv748x_csi2_get_pad_format(struct v4l2_subdev *sd,
> -			    struct v4l2_subdev_state *sd_state,
> -			    unsigned int pad, u32 which)
> -{
> -	struct adv748x_csi2 *tx = adv748x_sd_to_csi2(sd);
> -
> -	if (which == V4L2_SUBDEV_FORMAT_TRY)
> -		return v4l2_subdev_state_get_format(sd_state, pad);
> -
> -	return &tx->format;
> -}
> -
> -static int adv748x_csi2_get_format(struct v4l2_subdev *sd,
> -				   struct v4l2_subdev_state *sd_state,
> -				   struct v4l2_subdev_format *sdformat)
> -{
> -	struct adv748x_csi2 *tx = adv748x_sd_to_csi2(sd);
> -	struct adv748x_state *state = tx->state;
> -	struct v4l2_mbus_framefmt *mbusformat;
> -
> -	mbusformat = adv748x_csi2_get_pad_format(sd, sd_state, sdformat->pad,
> -						 sdformat->which);
> -	if (!mbusformat)
> -		return -EINVAL;
> -
> -	mutex_lock(&state->mutex);
> -
> -	sdformat->format = *mbusformat;
> -
> -	mutex_unlock(&state->mutex);
> -
> -	return 0;
> -}
> -
>  static int adv748x_csi2_set_format(struct v4l2_subdev *sd,
>  				   struct v4l2_subdev_state *sd_state,
>  				   struct v4l2_subdev_format *sdformat)
>  {
> -	struct adv748x_csi2 *tx = adv748x_sd_to_csi2(sd);
> -	struct adv748x_state *state = tx->state;
>  	struct v4l2_mbus_framefmt *mbusformat;
> -	int ret = 0;
> -
> -	mbusformat = adv748x_csi2_get_pad_format(sd, sd_state, sdformat->pad,
> -						 sdformat->which);
> -	if (!mbusformat)
> -		return -EINVAL;
>  
> -	mutex_lock(&state->mutex);
> +	mbusformat = v4l2_subdev_state_get_format(sd_state, sdformat->pad);
>  
> +	/* Format on the source pad is always copied from the sink one. */
>  	if (sdformat->pad == ADV748X_CSI2_SOURCE) {
>  		const struct v4l2_mbus_framefmt *sink_fmt;
>  
> -		sink_fmt = adv748x_csi2_get_pad_format(sd, sd_state,
> -						       ADV748X_CSI2_SINK,
> -						       sdformat->which);
> -
> -		if (!sink_fmt) {
> -			ret = -EINVAL;
> -			goto unlock;
> -		}
> -
> +		sink_fmt = v4l2_subdev_state_get_format(sd_state,
> +							ADV748X_CSI2_SINK);
>  		sdformat->format = *sink_fmt;

That's not the right way to do it. You should propagate the format from
sink to source when pad == ADV748X_CSI2_SINK, and return
adv748x_csi2_get_format() when pad == ADV748X_CSI2_SOURCE. Otherwise
setting the format on the sink pad will not update the state of the
source pad, and a get format call on the source pad will return an
incorrect format.

>  	}
>  
>  	*mbusformat = sdformat->format;
>  
> -unlock:
> -	mutex_unlock(&state->mutex);
> -
> -	return ret;
> +	return 0;
>  }
>  
>  static int adv748x_csi2_get_mbus_config(struct v4l2_subdev *sd, unsigned int pad,
> @@ -228,7 +176,7 @@ static int adv748x_csi2_get_mbus_config(struct v4l2_subdev *sd, unsigned int pad
>  }
>  
>  static const struct v4l2_subdev_pad_ops adv748x_csi2_pad_ops = {
> -	.get_fmt = adv748x_csi2_get_format,
> +	.get_fmt = v4l2_subdev_get_fmt,
>  	.set_fmt = adv748x_csi2_set_format,
>  	.get_mbus_config = adv748x_csi2_get_mbus_config,
>  };
> @@ -320,6 +268,11 @@ int adv748x_csi2_init(struct adv748x_state *state, struct adv748x_csi2 *tx)
>  	if (ret)
>  		goto err_cleanup_subdev;
>  
> +	tx->sd.state_lock = tx->ctrl_hdl.lock;

Maybe that's addressed in subsequent patches, but do we need a
device-wide lock ? The code you replace above uses the
adv748x_state.mutex lock, which covers all subdevs. I don't think this
patch introduces race conditions, so this could possibly be handled on
top.

> +	ret = v4l2_subdev_init_finalize(&tx->sd);
> +	if (ret)
> +		goto err_free_ctrl;
> +
>  	ret = v4l2_async_register_subdev(&tx->sd);
>  	if (ret)
>  		goto err_free_ctrl;
> diff --git a/drivers/media/i2c/adv748x/adv748x.h b/drivers/media/i2c/adv748x/adv748x.h
> index d2b5e722e997..9bc0121d0eff 100644
> --- a/drivers/media/i2c/adv748x/adv748x.h
> +++ b/drivers/media/i2c/adv748x/adv748x.h
> @@ -75,7 +75,6 @@ enum adv748x_csi2_pads {
>  
>  struct adv748x_csi2 {
>  	struct adv748x_state *state;
> -	struct v4l2_mbus_framefmt format;
>  	unsigned int page;
>  	unsigned int port;
>  	unsigned int num_lanes;

-- 
Regards,

Laurent Pinchart