linux-kernel - Re: [PATCH v3 06/15] media: rcar-csi2: Simplify rcsi2_calc

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Message-ID: <20250602094349.GG3645@pendragon.ideasonboard.com>
Date: Mon, 2 Jun 2025 12:43:49 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
Cc: Niklas Söderlund <niklas.soderlund@...natech.se>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Niklas Söderlund <niklas.soderlund+renesas@...natech.se>,
	Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
	Jacopo Mondi <jacopo.mondi@...asonboard.com>
Subject: Re: [PATCH v3 06/15] media: rcar-csi2: Simplify rcsi2_calc_mbps()

Hi Tomi,

Thank you for the patch.

On Fri, May 30, 2025 at 04:50:35PM +0300, Tomi Valkeinen wrote:
> Instead of taking the bpp and the number of lanes as parameters to
> rcsi2_calc_mbps(), change the function to get those parameters inside
> the function. This centralizes the code a bit and makes it easier to add
> streams support.

This comes at the cost of calling rcsi2_get_active_lanes() multiple
times. I will assume for now that subsequent patches will show that the
benefits outweight the cost.

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>

> Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
> ---
>  drivers/media/platform/renesas/rcar-csi2.c | 45 ++++++++++++++++--------------
>  1 file changed, 24 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/media/platform/renesas/rcar-csi2.c b/drivers/media/platform/renesas/rcar-csi2.c
> index 8aca35096408..90973f3cba38 100644
> --- a/drivers/media/platform/renesas/rcar-csi2.c
> +++ b/drivers/media/platform/renesas/rcar-csi2.c
> @@ -998,13 +998,18 @@ static int rcsi2_get_active_lanes(struct rcar_csi2 *priv,
>  	return 0;
>  }
>  
> -static int rcsi2_calc_mbps(struct rcar_csi2 *priv, unsigned int bpp,
> -			   unsigned int lanes)
> +static int rcsi2_calc_mbps(struct rcar_csi2 *priv,
> +			   struct v4l2_subdev_state *state)
>  {
> +	const struct rcar_csi2_format *format;
> +	struct v4l2_mbus_framefmt *fmt;
>  	struct media_pad *remote_pad;
>  	struct v4l2_subdev *source;
> +	unsigned int lanes;
> +	unsigned int bpp;
>  	s64 freq;
>  	u64 mbps;
> +	int ret;
>  
>  	if (!priv->remote)
>  		return -ENODEV;
> @@ -1012,6 +1017,20 @@ static int rcsi2_calc_mbps(struct rcar_csi2 *priv, unsigned int bpp,
>  	source = priv->remote;
>  	remote_pad = &source->entity.pads[priv->remote_pad];
>  
> +	ret = rcsi2_get_active_lanes(priv, &lanes);
> +	if (ret)
> +		return ret;
> +
> +	fmt = v4l2_subdev_state_get_format(state, RCAR_CSI2_SINK);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	format = rcsi2_code_to_fmt(fmt->code);
> +	if (!format)
> +		return -EINVAL;
> +
> +	bpp = format->bpp;
> +
>  	freq = v4l2_get_link_freq(remote_pad, bpp, 2 * lanes);
>  	if (freq < 0) {
>  		int ret = (int)freq;
> @@ -1092,7 +1111,7 @@ static int rcsi2_start_receiver_gen3(struct rcar_csi2 *priv,
>  	phycnt = PHYCNT_ENABLECLK;
>  	phycnt |= (1 << lanes) - 1;
>  
> -	mbps = rcsi2_calc_mbps(priv, format->bpp, lanes);
> +	mbps = rcsi2_calc_mbps(priv, state);
>  	if (mbps < 0)
>  		return mbps;
>  
> @@ -1300,23 +1319,15 @@ static int rcsi2_c_phy_setting_v4h(struct rcar_csi2 *priv, int msps)
>  static int rcsi2_start_receiver_v4h(struct rcar_csi2 *priv,
>  				    struct v4l2_subdev_state *state)
>  {
> -	const struct rcar_csi2_format *format;
> -	const struct v4l2_mbus_framefmt *fmt;
>  	unsigned int lanes;
>  	int msps;
>  	int ret;
>  
> -	/* Use the format on the sink pad to compute the receiver config. */
> -	fmt = v4l2_subdev_state_get_format(state, RCAR_CSI2_SINK);
> -	format = rcsi2_code_to_fmt(fmt->code);
> -	if (!format)
> -		return -EINVAL;
> -
>  	ret = rcsi2_get_active_lanes(priv, &lanes);
>  	if (ret)
>  		return ret;
>  
> -	msps = rcsi2_calc_mbps(priv, format->bpp, lanes);
> +	msps = rcsi2_calc_mbps(priv, state);
>  	if (msps < 0)
>  		return msps;
>  
> @@ -1494,23 +1505,15 @@ static int rcsi2_init_common_v4m(struct rcar_csi2 *priv, unsigned int mbps)
>  static int rcsi2_start_receiver_v4m(struct rcar_csi2 *priv,
>  				    struct v4l2_subdev_state *state)
>  {
> -	const struct rcar_csi2_format *format;
> -	const struct v4l2_mbus_framefmt *fmt;
>  	unsigned int lanes;
>  	int mbps;
>  	int ret;
>  
> -	/* Calculate parameters */
> -	fmt = v4l2_subdev_state_get_format(state, RCAR_CSI2_SINK);
> -	format = rcsi2_code_to_fmt(fmt->code);
> -	if (!format)
> -		return -EINVAL;
> -
>  	ret = rcsi2_get_active_lanes(priv, &lanes);
>  	if (ret)
>  		return ret;
>  
> -	mbps = rcsi2_calc_mbps(priv, format->bpp, lanes);
> +	mbps = rcsi2_calc_mbps(priv, state);
>  	if (mbps < 0)
>  		return mbps;
>  

-- 
Regards,

Laurent Pinchart