Re: [PATCH v7 1/5] media: v4l: Support passing media pad argument to v4l2_get_link_freq()

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

Hi Sakari,

Thank you for the patch.

On Tue, Dec 10, 2024 at 09:59:02AM +0200, Sakari Ailus wrote:
> v4l2_get_link_freq() accepts a V4L2 control handler for now, but it needs
> to take struct media_pad argument in order to obtain the link frequency
> using get_mbus_config() pad op. Prepare for this by allowing struct
> media_pad as well.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
>  drivers/media/v4l2-core/v4l2-common.c | 21 ++++++++++++++++++---
>  include/media/v4l2-common.h           | 19 ++++++++++++++++---
>  2 files changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> index 0a2f4f0d0a07..9fe74c7e064f 100644
> --- a/drivers/media/v4l2-core/v4l2-common.c
> +++ b/drivers/media/v4l2-core/v4l2-common.c
> @@ -466,8 +466,8 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat,
>  }
>  EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt);
>  
> -s64 v4l2_get_link_freq(struct v4l2_ctrl_handler *handler, unsigned int mul,
> -		       unsigned int div)
> +s64 __v4l2_get_link_freq_ctrl(struct v4l2_ctrl_handler *handler,
> +			      unsigned int mul, unsigned int div)
>  {
>  	struct v4l2_ctrl *ctrl;
>  	s64 freq;
> @@ -502,7 +502,22 @@ s64 v4l2_get_link_freq(struct v4l2_ctrl_handler *handler, unsigned int mul,
>  
>  	return freq > 0 ? freq : -EINVAL;
>  }
> -EXPORT_SYMBOL_GPL(v4l2_get_link_freq);
> +EXPORT_SYMBOL_GPL(__v4l2_get_link_freq_ctrl);
> +
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +s64 __v4l2_get_link_freq_pad(struct media_pad *pad, unsigned int mul,
> +			     unsigned int div)
> +{
> +	struct v4l2_subdev *sd;
> +
> +	sd = media_entity_to_v4l2_subdev(pad->entity);
> +	if (!sd)
> +		return -ENODEV;
> +
> +	return __v4l2_get_link_freq_ctrl(sd->ctrl_handler, mul, div);
> +}
> +EXPORT_SYMBOL_GPL(__v4l2_get_link_freq_pad);
> +#endif /* CONFIG_MEDIA_CONTROLLER */
>  
>  /*
>   * Simplify a fraction using a simple continued fraction decomposition. The
> diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h
> index 63ad36f04f72..fda903bb3674 100644
> --- a/include/media/v4l2-common.h
> +++ b/include/media/v4l2-common.h
> @@ -525,7 +525,8 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32 pixelformat,
>  /**
>   * v4l2_get_link_freq - Get link rate from transmitter
>   *
> - * @handler: The transmitter's control handler
> + * @pad: The transmitter's media pad (or control handler for non-MC users or
> + *	 compatibility reasons, don't use in new code)
>   * @mul: The multiplier between pixel rate and link frequency. Bits per pixel on
>   *	 D-PHY, samples per clock on parallel. 0 otherwise.
>   * @div: The divisor between pixel rate and link frequency. Number of data lanes
> @@ -541,8 +542,20 @@ int v4l2_fill_pixfmt_mp(struct v4l2_pix_format_mplane *pixfmt, u32 pixelformat,
>   * * %-ENOENT: Link frequency or pixel rate control not found
>   * * %-EINVAL: Invalid link frequency value
>   */
> -s64 v4l2_get_link_freq(struct v4l2_ctrl_handler *handler, unsigned int mul,
> -		       unsigned int div);
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +#define v4l2_get_link_freq(pad, mul, div)				\
> +	_Generic(pad,							\
> +		 struct media_pad *: __v4l2_get_link_freq_pad,		\
> +		 struct v4l2_ctrl_handler *: __v4l2_get_link_freq_ctrl)	\
> +	(pad, mul, div)
> +s64 __v4l2_get_link_freq_pad(struct media_pad *pad, unsigned int mul,
> +			     unsigned int div);
> +#else
> +#define v4l2_get_link_freq(handler, mul, div)		\
> +	__v4l2_get_link_freq_ctrl(handler, mul, div)
> +#endif
> +s64 __v4l2_get_link_freq_ctrl(struct v4l2_ctrl_handler *handler,
> +			      unsigned int mul, unsigned int div);

Let's avoid this complexity by patching callers. I'm OK with this patch
as a temporary measure, but the series should end with a patch that
removes the ability to pass a control handler.

>  
>  void v4l2_simplify_fraction(u32 *numerator, u32 *denominator,
>  		unsigned int n_terms, unsigned int threshold);

-- 
Regards,

Laurent Pinchart