Re: [PATCH v10 09/30] rcar-vin: read subdevice format for crop only when needed

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

Hi Niklas,

Thank you for the patch.

On Monday, 29 January 2018 18:34:14 EET Niklas Söderlund wrote:
> Instead of caching the subdevice format each time the video device
> format is set read it directly when it's needed. As it turns out the
> format is only needed when figuring out the max rectangle for cropping.
> 
> This simplifies the code and makes it clearer what the source format is
> used for.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> ---
>  drivers/media/platform/rcar-vin/rcar-v4l2.c | 112 +++++++++++++-----------
>  drivers/media/platform/rcar-vin/rcar-vin.h  |  12 ---
>  2 files changed, 61 insertions(+), 63 deletions(-)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> b/drivers/media/platform/rcar-vin/rcar-v4l2.c index
> c2265324c7c96308..4d5be2d0c79c9c9a 100644
> --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> @@ -90,35 +90,54 @@ static u32 rvin_format_sizeimage(struct v4l2_pix_format
> *pix) * V4L2
>   */
> 
> -static void rvin_reset_crop_compose(struct rvin_dev *vin)
> +static int rvin_get_source_format(struct rvin_dev *vin,
> +				  struct v4l2_mbus_framefmt *mbus_fmt)
>  {
> +	struct v4l2_subdev_format fmt = {
> +		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
> +		.pad = vin->digital->source_pad,
> +	};
> +	int ret;
> +
> +	ret = v4l2_subdev_call(vin_to_source(vin), pad, get_fmt, NULL, &fmt);
> +	if (ret)
> +		return ret;
> +
> +	memcpy(mbus_fmt, &fmt.format, sizeof(*mbus_fmt));

You can use

	*mbus_fmt = fmt.format;

That way the compiler will catch more mistakes, for instance incompatible 
types between the two arguments.

> +
> +	return 0;
> +}
> +
> +static int rvin_reset_crop_compose(struct rvin_dev *vin)
> +{
> +	struct v4l2_mbus_framefmt source_fmt;
> +	int ret;
> +
> +	ret = rvin_get_source_format(vin, &source_fmt);
> +	if (ret)
> +		return ret;
> +
>  	vin->crop.top = vin->crop.left = 0;
> -	vin->crop.width = vin->source.width;
> -	vin->crop.height = vin->source.height;
> +	vin->crop.width = source_fmt.width;
> +	vin->crop.height = source_fmt.height;
> 
>  	vin->compose.top = vin->compose.left = 0;
>  	vin->compose.width = vin->format.width;
>  	vin->compose.height = vin->format.height;
> +
> +	return 0;
>  }
> 
>  static int rvin_reset_format(struct rvin_dev *vin)
>  {
> -	struct v4l2_subdev_format fmt = {
> -		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
> -	};
> -	struct v4l2_mbus_framefmt *mf = &fmt.format;
> +	struct v4l2_mbus_framefmt source_fmt;
>  	int ret;
> 
> -	fmt.pad = vin->digital->source_pad;
> -
> -	ret = v4l2_subdev_call(vin_to_source(vin), pad, get_fmt, NULL, &fmt);
> +	ret = rvin_get_source_format(vin, &source_fmt);
>  	if (ret)
>  		return ret;

You retrieve the source format once here...

> -	vin->format.width	= mf->width;
> -	vin->format.height	= mf->height;
> -	vin->format.colorspace	= mf->colorspace;
> -	vin->format.field	= mf->field;
> +	v4l2_fill_pix_format(&vin->format, &source_fmt);
> 
>  	/*
>  	 * If the subdevice uses ALTERNATE field mode and G_STD is
> @@ -147,7 +166,9 @@ static int rvin_reset_format(struct rvin_dev *vin)
>  		break;
>  	}
> 
> -	rvin_reset_crop_compose(vin);
> +	ret = rvin_reset_crop_compose(vin);

... and this function then retrieves it a second time. Can't you pass it to 
rvin_reset_crop_compose() ? If the source changes its format autonomously 
between the two calls you'll end up with an inconsistent result otherwise.

> +	if (ret)
> +		return ret;
> 
>  	vin->format.bytesperline = rvin_format_bytesperline(&vin->format);
>  	vin->format.sizeimage = rvin_format_sizeimage(&vin->format);
> @@ -156,9 +177,7 @@ static int rvin_reset_format(struct rvin_dev *vin)
>  }
> 
>  static int __rvin_try_format_source(struct rvin_dev *vin,
> -				    u32 which,
> -				    struct v4l2_pix_format *pix,
> -				    struct rvin_source_fmt *source)
> +				    u32 which, struct v4l2_pix_format *pix)
>  {
>  	struct v4l2_subdev *sd;
>  	struct v4l2_subdev_pad_config *pad_cfg;
> @@ -190,25 +209,16 @@ static int __rvin_try_format_source(struct rvin_dev
> *vin,
> 
>  	v4l2_fill_pix_format(pix, &format.format);
> 
> -	source->width = pix->width;
> -	source->height = pix->height;
> -
>  	pix->field = field;
>  	pix->width = width;
>  	pix->height = height;
> -
> -	vin_dbg(vin, "Source resolution: %ux%u\n", source->width,
> -		source->height);
> -
>  done:
>  	v4l2_subdev_free_pad_config(pad_cfg);
>  	return ret;
>  }
> 
>  static int __rvin_try_format(struct rvin_dev *vin,
> -			     u32 which,
> -			     struct v4l2_pix_format *pix,
> -			     struct rvin_source_fmt *source)
> +			     u32 which, struct v4l2_pix_format *pix)
>  {
>  	u32 walign;
>  	int ret;
> @@ -229,7 +239,7 @@ static int __rvin_try_format(struct rvin_dev *vin,
>  	pix->sizeimage = 0;
> 
>  	/* Limit to source capabilities */
> -	ret = __rvin_try_format_source(vin, which, pix, source);
> +	ret = __rvin_try_format_source(vin, which, pix);
>  	if (ret)
>  		return ret;
> 
> @@ -238,7 +248,6 @@ static int __rvin_try_format(struct rvin_dev *vin,
>  	case V4L2_FIELD_BOTTOM:
>  	case V4L2_FIELD_ALTERNATE:
>  		pix->height /= 2;
> -		source->height /= 2;
>  		break;
>  	case V4L2_FIELD_NONE:
>  	case V4L2_FIELD_INTERLACED_TB:
> @@ -290,35 +299,26 @@ static int rvin_try_fmt_vid_cap(struct file *file,
> void *priv, struct v4l2_format *f)
>  {
>  	struct rvin_dev *vin = video_drvdata(file);
> -	struct rvin_source_fmt source;
> 
> -	return __rvin_try_format(vin, V4L2_SUBDEV_FORMAT_TRY, &f->fmt.pix,
> -				 &source);
> +	return __rvin_try_format(vin, V4L2_SUBDEV_FORMAT_TRY, &f->fmt.pix);
>  }
> 
>  static int rvin_s_fmt_vid_cap(struct file *file, void *priv,
>  			      struct v4l2_format *f)
>  {
>  	struct rvin_dev *vin = video_drvdata(file);
> -	struct rvin_source_fmt source;
>  	int ret;
> 
>  	if (vb2_is_busy(&vin->queue))
>  		return -EBUSY;
> 
> -	ret = __rvin_try_format(vin, V4L2_SUBDEV_FORMAT_ACTIVE, &f->fmt.pix,
> -				&source);
> +	ret = __rvin_try_format(vin, V4L2_SUBDEV_FORMAT_ACTIVE, &f->fmt.pix);
>  	if (ret)
>  		return ret;
> 
> -	vin->source.width = source.width;
> -	vin->source.height = source.height;
> -
>  	vin->format = f->fmt.pix;
> 
> -	rvin_reset_crop_compose(vin);
> -
> -	return 0;
> +	return rvin_reset_crop_compose(vin);

Same here, I think you should pass the format that has been retrieved by 
__rvin_try_format().

If you want to get rid of the rvin_source_fmt structure (and I think we 
should) then I wouldn't mind if you used v4l2_rect. Another option would be to 
propose a v4l2_size, but that would be one additional dependency.

>  }
> 
>  static int rvin_g_fmt_vid_cap(struct file *file, void *priv,
> @@ -346,6 +346,8 @@ static int rvin_g_selection(struct file *file, void *fh,
> struct v4l2_selection *s)
>  {
>  	struct rvin_dev *vin = video_drvdata(file);
> +	struct v4l2_mbus_framefmt source_fmt;
> +	int ret;
> 
>  	if (s->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
>  		return -EINVAL;
> @@ -353,9 +355,12 @@ static int rvin_g_selection(struct file *file, void
> *fh, switch (s->target) {
>  	case V4L2_SEL_TGT_CROP_BOUNDS:
>  	case V4L2_SEL_TGT_CROP_DEFAULT:
> +		ret = rvin_get_source_format(vin, &source_fmt);
> +		if (ret)
> +			return ret;
>  		s->r.left = s->r.top = 0;
> -		s->r.width = vin->source.width;
> -		s->r.height = vin->source.height;
> +		s->r.width = source_fmt.width;
> +		s->r.height = source_fmt.height;
>  		break;
>  	case V4L2_SEL_TGT_CROP:
>  		s->r = vin->crop;
> @@ -380,6 +385,7 @@ static int rvin_s_selection(struct file *file, void *fh,
> struct v4l2_selection *s)
>  {
>  	struct rvin_dev *vin = video_drvdata(file);
> +	struct v4l2_mbus_framefmt source_fmt;
>  	const struct rvin_video_format *fmt;
>  	struct v4l2_rect r = s->r;
>  	struct v4l2_rect max_rect;
> @@ -387,6 +393,7 @@ static int rvin_s_selection(struct file *file, void *fh,
> .width = 6,
>  		.height = 2,
>  	};
> +	int ret;
> 
>  	if (s->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
>  		return -EINVAL;
> @@ -396,22 +403,25 @@ static int rvin_s_selection(struct file *file, void
> *fh, switch (s->target) {
>  	case V4L2_SEL_TGT_CROP:
>  		/* Can't crop outside of source input */
> +		ret = rvin_get_source_format(vin, &source_fmt);
> +		if (ret)
> +			return ret;

If you stop caching the source format you'll end up validating the crop 
rectangle against the current source format. What will happen if the format 
changed since the last VIDIOC_S_FMT call ?

And thinking about it, are sources allowed to change their format autonomously 
? They surely can detect format changes, but can they update the format 
without notifying anyone ? Looking at the adv7180 driver for instance, the 
format depends on the TV standard, but the driver doesn't change it. It only 
reports newly detected standards and relies on someone then calling the s_std 
operation.

>  		max_rect.top = max_rect.left = 0;
> -		max_rect.width = vin->source.width;
> -		max_rect.height = vin->source.height;
> +		max_rect.width = source_fmt.width;
> +		max_rect.height = source_fmt.height;
>  		v4l2_rect_map_inside(&r, &max_rect);
> 
> -		v4l_bound_align_image(&r.width, 2, vin->source.width, 1,
> -				      &r.height, 4, vin->source.height, 2, 0);
> +		v4l_bound_align_image(&r.width, 2, source_fmt.width, 1,
> +				      &r.height, 4, source_fmt.height, 2, 0);
> 
> -		r.top  = clamp_t(s32, r.top, 0, vin->source.height - r.height);
> -		r.left = clamp_t(s32, r.left, 0, vin->source.width - r.width);
> +		r.top  = clamp_t(s32, r.top, 0, source_fmt.height - r.height);
> +		r.left = clamp_t(s32, r.left, 0, source_fmt.width - r.width);
> 
>  		vin->crop = s->r = r;
> 
>  		vin_dbg(vin, "Cropped %dx%d@%d:%d of %dx%d\n",
>  			r.width, r.height, r.left, r.top,
> -			vin->source.width, vin->source.height);
> +			source_fmt.width, source_fmt.height);
>  		break;
>  	case V4L2_SEL_TGT_COMPOSE:
>  		/* Make sure compose rect fits inside output format */
> diff --git a/drivers/media/platform/rcar-vin/rcar-vin.h
> b/drivers/media/platform/rcar-vin/rcar-vin.h index
> 8daba9db0e927a49..39051da31650bd79 100644
> --- a/drivers/media/platform/rcar-vin/rcar-vin.h
> +++ b/drivers/media/platform/rcar-vin/rcar-vin.h
> @@ -48,16 +48,6 @@ enum rvin_dma_state {
>  	STOPPING,
>  };
> 
> -/**
> - * struct rvin_source_fmt - Source information
> - * @width:	Width from source
> - * @height:	Height from source
> - */
> -struct rvin_source_fmt {
> -	u32 width;
> -	u32 height;
> -};
> -
>  /**
>   * struct rvin_video_format - Data format stored in memory
>   * @fourcc:	Pixelformat
> @@ -124,7 +114,6 @@ struct rvin_info {
>   * @sequence:		V4L2 buffers sequence number
>   * @state:		keeps track of operation state
>   *
> - * @source:		active format from the video source
>   * @format:		active V4L2 pixel format
>   *
>   * @crop:		active cropping
> @@ -151,7 +140,6 @@ struct rvin_dev {
>  	unsigned int sequence;
>  	enum rvin_dma_state state;
> 
> -	struct rvin_source_fmt source;
>  	struct v4l2_pix_format format;
> 
>  	struct v4l2_rect crop;

-- 
Regards,

Laurent Pinchart