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Date:   Thu, 10 Feb 2022 19:43:09 +0100
From:   Jacopo Mondi <jacopo@jmondi.org>
To:     Eugen Hristev <eugen.hristev@microchip.com>
Cc:     robh+dt@kernel.org, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, jacopo+renesas@jmondi.org,
        hverkuil-cisco@xs4all.nl, nicolas.ferre@microchip.com,
        sakari.ailus@iki.fi, laurent.pinchart@ideasonboard.com
Subject: Re: [PATCH v4 07/11] media: atmel: atmel-isc: change format
 propagation to subdev into only verification
Message-ID: <20220210184309.5ifihhnb4qmahdy5@uno.localdomain>
References: <20220121131416.603972-1-eugen.hristev@microchip.com>
 <20220121131416.603972-8-eugen.hristev@microchip.com>
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In-Reply-To: <20220121131416.603972-8-eugen.hristev@microchip.com>
Precedence: bulk

Hi Eugen

On Fri, Jan 21, 2022 at 03:14:12PM +0200, Eugen Hristev wrote:
> As a top MC video driver, the atmel-isc should not propagate the format to the
> subdevice.
> It should rather check at start_streaming() time if the subdev is properly
> configured with a compatible format.
> Removed the whole format finding logic, and reworked the format verification
> at start_streaming time, such that the ISC will return an error if the subdevice
> is not properly configured. To achieve this, media_pipeline_start
> is called and a link_validate callback is created to check the formats.
> With this being done, the module parameter 'sensor_preferred' makes no sense
> anymore. The ISC should not decide which format the sensor is using. The
> ISC should only cope with the situation and inform userspace if the streaming
> is possible in the current configuration.

This sounds right!

> The redesign of the format propagation has also risen the question of the
> enumfmt callback. If enumfmt is called with an mbus_code, the enumfmt handler
> should only return the formats that are supported for this mbus_code.
> To make it more easy to understand the formats, changed the report order
> to report first the native formats, and after that the formats that the ISC
> can convert to.
>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
> Changes in v4:
> - moved validation code into link_validate and used media_pipeline_start
> - merged this patch with the enum_fmt patch which was previously in v3 of
> the series
>
> Changes in v3:
> - clamp to maximum resolution once the frame size from the subdev is found
>
>  drivers/media/platform/atmel/atmel-isc-base.c | 335 ++++++++++--------
>  .../media/platform/atmel/atmel-isc-scaler.c   |   5 +
>  drivers/media/platform/atmel/atmel-isc.h      |   3 +
>  3 files changed, 191 insertions(+), 152 deletions(-)
>
> diff --git a/drivers/media/platform/atmel/atmel-isc-base.c b/drivers/media/platform/atmel/atmel-isc-base.c
> index f7a88399bd54..31c79313aadc 100644
> --- a/drivers/media/platform/atmel/atmel-isc-base.c
> +++ b/drivers/media/platform/atmel/atmel-isc-base.c
> @@ -36,11 +36,6 @@ static unsigned int debug;
>  module_param(debug, int, 0644);
>  MODULE_PARM_DESC(debug, "debug level (0-2)");
>
> -static unsigned int sensor_preferred = 1;
> -module_param(sensor_preferred, uint, 0644);
> -MODULE_PARM_DESC(sensor_preferred,
> -		 "Sensor is preferred to output the specified format (1-on 0-off), default 1");
> -
>  #define ISC_IS_FORMAT_RAW(mbus_code) \
>  	(((mbus_code) & 0xf000) == 0x3000)
>
> @@ -337,6 +332,10 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
>  	unsigned long flags;
>  	int ret;
>
> +	ret = media_pipeline_start(&isc->video_dev.entity, &isc->mpipe);
> +	if (ret)
> +		goto err_pipeline_start;
> +
>  	/* Enable stream on the sub device */
>  	ret = v4l2_subdev_call(isc->current_subdev->sd, video, s_stream, 1);
>  	if (ret && ret != -ENOIOCTLCMD) {
> @@ -384,6 +383,9 @@ static int isc_start_streaming(struct vb2_queue *vq, unsigned int count)
>  	v4l2_subdev_call(isc->current_subdev->sd, video, s_stream, 0);
>
>  err_start_stream:
> +	media_pipeline_stop(&isc->video_dev.entity);
> +
> +err_pipeline_start:
>  	spin_lock_irqsave(&isc->dma_queue_lock, flags);
>  	list_for_each_entry(buf, &isc->dma_queue, list)
>  		vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> @@ -420,6 +422,9 @@ static void isc_stop_streaming(struct vb2_queue *vq)
>  	if (ret && ret != -ENOIOCTLCMD)
>  		v4l2_err(&isc->v4l2_dev, "stream off failed in subdev\n");
>
> +	/* Stop media pipeline */
> +	media_pipeline_stop(&isc->video_dev.entity);
> +
>  	/* Release all active buffers */
>  	spin_lock_irqsave(&isc->dma_queue_lock, flags);
>  	if (unlikely(isc->cur_frm)) {
> @@ -496,21 +501,56 @@ static int isc_enum_fmt_vid_cap(struct file *file, void *priv,
>  	u32 index = f->index;
>  	u32 i, supported_index;
>
> -	if (index < isc->controller_formats_size) {
> -		f->pixelformat = isc->controller_formats[index].fourcc;
> -		return 0;
> +	supported_index = 0;
> +
> +	for (i = 0; i < isc->formats_list_size; i++) {
> +		if (!isc->formats_list[i].sd_support)
> +			continue;

Sorry to ask again about sd_support, but if the ISC formats
enumeration is not constrained to a specific mbus_code, shouldn't all
the formats be enumerated regardless if they're supported from the
sensor or not ?

> +		/*
> +		 * If specific mbus_code is requested, provide only
> +		 * supported formats with this mbus code
> +		 */
> +		if (f->mbus_code && f->mbus_code !=
> +		    isc->formats_list[i].mbus_code)

nit: for clarity
		if (f->mbus_code &&
                    f->mbus_code != isc->formats_list[i].mbus_code)

> +			continue;
> +		if (supported_index == index) {
> +			f->pixelformat = isc->formats_list[i].fourcc;
> +			return 0;
> +		}
> +		supported_index++;
>  	}
>
> -	index -= isc->controller_formats_size;
> +	/*
> +	 * If the sensor does not support this mbus_code whatsoever,
> +	 * there is no reason to advertise any of our output formats
> +	 */
> +	if (supported_index == 0)
> +		return -EINVAL;
>
> +	/*
> +	 * If the sensor uses a format that is not raw, then we cannot
> +	 * convert it to any of the formats that we usually can with a
> +	 * RAW sensor. Thus, do not advertise them.
> +	 */
> +	if (isc->config.sd_format &&
> +	    !ISC_IS_FORMAT_RAW(isc->config.sd_format->mbus_code))
> +		return -EINVAL;
> +
> +	/*
> +	 * Iterate again through the formats that we can convert to.
> +	 * However, to avoid duplicates, skip the formats that
> +	 * the sensor already supports directly
> +	 */
> +	index -= supported_index;
>  	supported_index = 0;
>
> -	for (i = 0; i < isc->formats_list_size; i++) {
> -		if (!ISC_IS_FORMAT_RAW(isc->formats_list[i].mbus_code) ||
> -		    !isc->formats_list[i].sd_support)
> +	for (i = 0; i < isc->controller_formats_size; i++) {
> +		/* if this format is already supported by sensor, skip it */
> +		if (find_format_by_fourcc(isc, isc->controller_formats[i].fourcc))
>  			continue;
>  		if (supported_index == index) {
> -			f->pixelformat = isc->formats_list[i].fourcc;
> +			f->pixelformat =
> +				isc->controller_formats[i].fourcc;

I trust this last part to work correctly, as it's not 100% clear to me :)

>  			return 0;
>  		}
>  		supported_index++;
> @@ -581,20 +621,30 @@ static int isc_try_validate_formats(struct isc_device *isc)
>  		break;
>  	default:
>  	/* any other different formats are not supported */
> +		v4l2_err(&isc->v4l2_dev, "Requested unsupported format.\n");
>  		ret = -EINVAL;
>  	}
>  	v4l2_dbg(1, debug, &isc->v4l2_dev,
>  		 "Format validation, requested rgb=%u, yuv=%u, grey=%u, bayer=%u\n",
>  		 rgb, yuv, grey, bayer);
>
> -	/* we cannot output RAW if we do not receive RAW */
> -	if ((bayer) && !ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code))
> +	if ((bayer) &&

just 'bayer' ?

> +	    !ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code)) {
> +		v4l2_err(&isc->v4l2_dev, "Cannot output RAW if we do not receive RAW.\n");
>  		return -EINVAL;
> +	}
>
> -	/* we cannot output GREY if we do not receive RAW/GREY */
>  	if (grey && !ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code) &&
> -	    !ISC_IS_FORMAT_GREY(isc->try_config.sd_format->mbus_code))
> +	    !ISC_IS_FORMAT_GREY(isc->try_config.sd_format->mbus_code)) {
> +		v4l2_err(&isc->v4l2_dev, "Cannot output GREY if we do not receive RAW/GREY.\n");
> +		return -EINVAL;
> +	}
> +
> +	if ((rgb || bayer || yuv) &&
> +	    ISC_IS_FORMAT_GREY(isc->try_config.sd_format->mbus_code)) {
> +		v4l2_err(&isc->v4l2_dev, "Cannot convert GREY to another format.\n");
>  		return -EINVAL;
> +	}
>
>  	return ret;
>  }
> @@ -822,7 +872,7 @@ static void isc_try_fse(struct isc_device *isc,
>  	 * If we do not know yet which format the subdev is using, we cannot
>  	 * do anything.
>  	 */
> -	if (!isc->try_config.sd_format)
> +	if (!isc->config.sd_format)
>  		return;
>
>  	fse.code = isc->try_config.sd_format->mbus_code;
> @@ -843,180 +893,141 @@ static void isc_try_fse(struct isc_device *isc,
>  	}
>  }
>
> -static int isc_try_fmt(struct isc_device *isc, struct v4l2_format *f,
> -			u32 *code)
> +static int isc_try_fmt(struct isc_device *isc, struct v4l2_format *f)
>  {
> -	int i;
> -	struct isc_format *sd_fmt = NULL, *direct_fmt = NULL;
>  	struct v4l2_pix_format *pixfmt = &f->fmt.pix;
> -	struct v4l2_subdev_pad_config pad_cfg = {};
> -	struct v4l2_subdev_state pad_state = {
> -		.pads = &pad_cfg
> -		};
> -	struct v4l2_subdev_format format = {
> -		.which = V4L2_SUBDEV_FORMAT_TRY,
> -	};
> -	u32 mbus_code;
> -	int ret;
> -	bool rlp_dma_direct_dump = false;
> +	unsigned int i;
>
>  	if (f->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
>  		return -EINVAL;
>
> -	/* Step 1: find a RAW format that is supported */
> -	for (i = 0; i < isc->num_user_formats; i++) {
> -		if (ISC_IS_FORMAT_RAW(isc->user_formats[i]->mbus_code)) {
> -			sd_fmt = isc->user_formats[i];
> +	isc->try_config.fourcc = isc->user_formats[0]->fourcc;
> +
> +	/* find if the format requested is supported */
> +	for (i = 0; i < isc->controller_formats_size; i++)
> +		if (isc->controller_formats[i].fourcc == pixfmt->pixelformat) {
> +			isc->try_config.fourcc = pixfmt->pixelformat;
>  			break;
>  		}
> -	}
> -	/* Step 2: We can continue with this RAW format, or we can look
> -	 * for better: maybe sensor supports directly what we need.
> -	 */
> -	direct_fmt = find_format_by_fourcc(isc, pixfmt->pixelformat);
> -
> -	/* Step 3: We have both. We decide given the module parameter which
> -	 * one to use.
> -	 */
> -	if (direct_fmt && sd_fmt && sensor_preferred)
> -		sd_fmt = direct_fmt;
> -
> -	/* Step 4: we do not have RAW but we have a direct format. Use it. */
> -	if (direct_fmt && !sd_fmt)
> -		sd_fmt = direct_fmt;
> -
> -	/* Step 5: if we are using a direct format, we need to package
> -	 * everything as 8 bit data and just dump it
> -	 */
> -	if (sd_fmt == direct_fmt)
> -		rlp_dma_direct_dump = true;
> -
> -	/* Step 6: We have no format. This can happen if the userspace
> -	 * requests some weird/invalid format.
> -	 * In this case, default to whatever we have
> -	 */
> -	if (!sd_fmt && !direct_fmt) {
> -		sd_fmt = isc->user_formats[isc->num_user_formats - 1];
> -		v4l2_dbg(1, debug, &isc->v4l2_dev,
> -			 "Sensor not supporting %.4s, using %.4s\n",
> -			 (char *)&pixfmt->pixelformat, (char *)&sd_fmt->fourcc);
> -	}
> -
> -	if (!sd_fmt) {
> -		ret = -EINVAL;
> -		goto isc_try_fmt_err;
> -	}
> -
> -	/* Step 7: Print out what we decided for debugging */
> -	v4l2_dbg(1, debug, &isc->v4l2_dev,
> -		 "Preferring to have sensor using format %.4s\n",
> -		 (char *)&sd_fmt->fourcc);
> -
> -	/* Step 8: at this moment we decided which format the subdev will use */
> -	isc->try_config.sd_format = sd_fmt;
> -
> -	/* Limit to Atmel ISC hardware capabilities */
> -	if (pixfmt->width > isc->max_width)
> -		pixfmt->width = isc->max_width;
> -	if (pixfmt->height > isc->max_height)
> -		pixfmt->height = isc->max_height;
> -
> -	/*
> -	 * The mbus format is the one the subdev outputs.
> -	 * The pixels will be transferred in this format Sensor -> ISC
> -	 */
> -	mbus_code = sd_fmt->mbus_code;
> -
> -	/*
> -	 * Validate formats. If the required format is not OK, default to raw.
> -	 */
> -
> -	isc->try_config.fourcc = pixfmt->pixelformat;
> -
> -	if (isc_try_validate_formats(isc)) {
> -		pixfmt->pixelformat = isc->try_config.fourcc = sd_fmt->fourcc;
> -		/* Re-try to validate the new format */
> -		ret = isc_try_validate_formats(isc);
> -		if (ret)
> -			goto isc_try_fmt_err;
> -	}
> -
> -	ret = isc_try_configure_rlp_dma(isc, rlp_dma_direct_dump);
> -	if (ret)
> -		goto isc_try_fmt_err;
> -
> -	ret = isc_try_configure_pipeline(isc);
> -	if (ret)
> -		goto isc_try_fmt_err;
>
> -	/* Obtain frame sizes if possible to have crop requirements ready */
> -	isc_try_fse(isc, &pad_state);
> -
> -	v4l2_fill_mbus_format(&format.format, pixfmt, mbus_code);
> -	ret = v4l2_subdev_call(isc->current_subdev->sd, pad, set_fmt,
> -			       &pad_state, &format);
> -	if (ret < 0)
> -		goto isc_try_fmt_subdev_err;
> +	/* If we did not find the requested format, we will fallback here */
> +	pixfmt->pixelformat = isc->try_config.fourcc;
> +	pixfmt->colorspace = V4L2_COLORSPACE_SRGB;
> +	pixfmt->field = V4L2_FIELD_NONE;
>
> -	v4l2_fill_pix_format(pixfmt, &format.format);
> +	isc_try_configure_rlp_dma(isc, false);
>
>  	/* Limit to Atmel ISC hardware capabilities */
> -	if (pixfmt->width > isc->max_width)
> -		pixfmt->width = isc->max_width;
> -	if (pixfmt->height > isc->max_height)
> -		pixfmt->height = isc->max_height;
> +	v4l_bound_align_image(&pixfmt->width, 16, isc->max_width, 0,
> +			      &pixfmt->height, 16, isc->max_height, 0, 0);
>
>  	pixfmt->field = V4L2_FIELD_NONE;
>  	pixfmt->bytesperline = (pixfmt->width * isc->try_config.bpp_v4l2) >> 3;
>  	pixfmt->sizeimage = ((pixfmt->width * isc->try_config.bpp) >> 3) *
>  			     pixfmt->height;

Seems pixfmt->field is set twice.

Could you move the assignment of all pixfmt to a single block ?

>
> -	if (code)
> -		*code = mbus_code;
> +	isc->try_fmt = *f;
>
>  	return 0;
> +}
>
> -isc_try_fmt_err:
> -	v4l2_err(&isc->v4l2_dev, "Could not find any possible format for a working pipeline\n");
> -isc_try_fmt_subdev_err:
> -	memset(&isc->try_config, 0, sizeof(isc->try_config));
> +static int isc_set_fmt(struct isc_device *isc, struct v4l2_format *f)
> +{
> +	isc_try_fmt(isc, f);
>
> -	return ret;
> +	/* make the try configuration active */
> +	isc->config = isc->try_config;
> +	isc->fmt = isc->try_fmt;
> +
> +	v4l2_dbg(1, debug, &isc->v4l2_dev, "ISC set_fmt to %.4s @%dx%d\n",
> +		 (char *)&f->fmt.pix.pixelformat,
> +		 f->fmt.pix.width, f->fmt.pix.height);
> +
> +	return 0;
>  }
>
> -static int isc_set_fmt(struct isc_device *isc, struct v4l2_format *f)
> +static int isc_validate(struct isc_device *isc)
>  {
> +	int ret;
> +	int i;
> +	struct isc_format *sd_fmt = NULL;
> +	struct v4l2_pix_format *pixfmt = &isc->fmt.fmt.pix;
>  	struct v4l2_subdev_format format = {
>  		.which = V4L2_SUBDEV_FORMAT_ACTIVE,
> +		.pad = isc->remote_pad,
> +	};
> +	struct v4l2_subdev_pad_config pad_cfg = {};
> +	struct v4l2_subdev_state pad_state = {
> +		.pads = &pad_cfg,
>  	};
> -	u32 mbus_code = 0;
> -	int ret;
>
> -	ret = isc_try_fmt(isc, f, &mbus_code);
> +	/* Get current format from subdev */
> +	ret = v4l2_subdev_call(isc->current_subdev->sd, pad, get_fmt, NULL,
> +			       &format);
>  	if (ret)
>  		return ret;
>
> -	v4l2_fill_mbus_format(&format.format, &f->fmt.pix, mbus_code);
> -	ret = v4l2_subdev_call(isc->current_subdev->sd, pad,
> -			       set_fmt, NULL, &format);
> -	if (ret < 0)
> -		return ret;
> +	/* Identify the subdev's format configuration */
> +	for (i = 0; i < isc->num_user_formats; i++)
> +		if (isc->user_formats[i]->mbus_code == format.format.code) {
> +			sd_fmt = isc->user_formats[i];
> +			break;
> +		}
> +
> +	/* Check if the format is not supported */
> +	if (!sd_fmt) {
> +		v4l2_err(&isc->v4l2_dev,
> +			 "Current subdevice is streaming a media bus code that is not supported 0x%x\n",
> +			 format.format.code);
> +		return -EPIPE;
> +	}
> +
> +	/* At this moment we know which format the subdev will use */
> +	isc->try_config.sd_format = sd_fmt;
> +
> +	/* If the sensor is not RAW, we can only do a direct dump */
> +	if (!ISC_IS_FORMAT_RAW(isc->try_config.sd_format->mbus_code))
> +		isc_try_configure_rlp_dma(isc, true);
>
>  	/* Limit to Atmel ISC hardware capabilities */
> -	if (f->fmt.pix.width > isc->max_width)
> -		f->fmt.pix.width = isc->max_width;
> -	if (f->fmt.pix.height > isc->max_height)
> -		f->fmt.pix.height = isc->max_height;
> +	v4l_bound_align_image(&format.format.width, 16, isc->max_width, 0,
> +			      &format.format.height, 16, isc->max_height, 0, 0);
> +
> +	/* Check if the frame size is the same. Otherwise we may overflow */
> +	if (pixfmt->height != format.format.height ||
> +	    pixfmt->width != format.format.width) {
> +		v4l2_err(&isc->v4l2_dev,
> +			 "ISC not configured with the proper frame size: %dx%d\n",
> +			 format.format.width, format.format.height);
> +		return -EPIPE;
> +	}
>
> -	isc->fmt = *f;
> +	v4l2_dbg(1, debug, &isc->v4l2_dev,
> +		 "Identified subdev using format %.4s with %dx%d %d bpp\n",
> +		 (char *)&sd_fmt->fourcc, pixfmt->width, pixfmt->height,
> +		 isc->try_config.bpp);
>
> +	/* Reset and restart AWB if the subdevice changed the format */
>  	if (isc->try_config.sd_format && isc->config.sd_format &&
>  	    isc->try_config.sd_format != isc->config.sd_format) {
>  		isc->ctrls.hist_stat = HIST_INIT;
>  		isc_reset_awb_ctrls(isc);
>  		isc_update_v4l2_ctrls(isc);
>  	}
> -	/* make the try configuration active */
> +
> +	/* Validate formats */
> +	ret = isc_try_validate_formats(isc);
> +	if (ret)
> +		return ret;
> +
> +	/* Obtain frame sizes if possible to have crop requirements ready */
> +	isc_try_fse(isc, &pad_state);
> +
> +	/* Configure ISC pipeline for the config */
> +	ret = isc_try_configure_pipeline(isc);
> +	if (ret)
> +		return ret;
> +
>  	isc->config = isc->try_config;
>
>  	v4l2_dbg(1, debug, &isc->v4l2_dev, "New ISC configuration in place\n");
> @@ -1040,7 +1051,7 @@ static int isc_try_fmt_vid_cap(struct file *file, void *priv,
>  {
>  	struct isc_device *isc = video_drvdata(file);
>
> -	return isc_try_fmt(isc, f, NULL);
> +	return isc_try_fmt(isc, f);
>  }
>
>  static int isc_enum_input(struct file *file, void *priv,
> @@ -1841,7 +1852,7 @@ static int isc_set_default_fmt(struct isc_device *isc)
>  	};
>  	int ret;
>
> -	ret = isc_try_fmt(isc, &f, NULL);
> +	ret = isc_try_fmt(isc, &f);
>  	if (ret)
>  		return ret;
>
> @@ -2015,6 +2026,24 @@ int isc_pipeline_init(struct isc_device *isc)
>  }
>  EXPORT_SYMBOL_GPL(isc_pipeline_init);
>
> +int isc_link_validate(struct media_link *link)
> +{
> +	struct video_device *vdev =
> +		media_entity_to_video_device(link->sink->entity);
> +	struct isc_device *isc = video_get_drvdata(vdev);
> +	int ret;
> +
> +	ret = v4l2_subdev_link_validate(link);
> +	if (ret)
> +		return ret;

Doesn't v4l2_subdev_link_validate() call
v4l2_subdev_link_validate_default() if you don't define a .link_validate()
pad operation ? v4l2_subdev_link_validate_default() compares format
and sizes of both ends to the links and want them to be identical,
something that defeat the purpose of your custom isc_validate() ?

Thanks
  j

> +
> +	return isc_validate(isc);
> +}
> +
> +static const struct media_entity_operations isc_entity_operations = {
> +	.link_validate = isc_link_validate,
> +};
> +
};
>  int isc_mc_init(struct isc_device *isc, u32 ver)
>  {
>  	const struct of_device_id *match;
> @@ -2022,6 +2051,8 @@ int isc_mc_init(struct isc_device *isc, u32 ver)
>
>  	isc->video_dev.entity.function = MEDIA_ENT_F_IO_V4L;
>  	isc->video_dev.entity.flags = MEDIA_ENT_FL_DEFAULT;
> +	isc->video_dev.entity.ops = &isc_entity_operations;
> +
>  	isc->pads[ISC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
>
>  	ret = media_entity_pads_init(&isc->video_dev.entity, ISC_PADS_NUM,
> diff --git a/drivers/media/platform/atmel/atmel-isc-scaler.c b/drivers/media/platform/atmel/atmel-isc-scaler.c
> index ec95c9665883..93375a61aea6 100644
> --- a/drivers/media/platform/atmel/atmel-isc-scaler.c
> +++ b/drivers/media/platform/atmel/atmel-isc-scaler.c
> @@ -155,6 +155,10 @@ static const struct v4l2_subdev_pad_ops isc_scaler_pad_ops = {
>  	.init_cfg = isc_scaler_init_cfg,
>  };
>
> +static const struct media_entity_operations isc_scaler_entity_ops = {
> +	.link_validate = v4l2_subdev_link_validate,
> +};
> +
>  static const struct v4l2_subdev_ops xisc_scaler_subdev_ops = {
>  	.pad = &isc_scaler_pad_ops,
>  };
> @@ -172,6 +176,7 @@ int isc_scaler_init(struct isc_device *isc)
>
>  	isc->scaler_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
>  	isc->scaler_sd.entity.function = MEDIA_ENT_F_PROC_VIDEO_SCALER;
> +	isc->scaler_sd.entity.ops = &isc_scaler_entity_ops;
>  	isc->scaler_pads[ISC_SCALER_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
>  	isc->scaler_pads[ISC_SCALER_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
>
> diff --git a/drivers/media/platform/atmel/atmel-isc.h b/drivers/media/platform/atmel/atmel-isc.h
> index 04ea5e340808..e36cf9d3942a 100644
> --- a/drivers/media/platform/atmel/atmel-isc.h
> +++ b/drivers/media/platform/atmel/atmel-isc.h
> @@ -270,6 +270,7 @@ enum isc_scaler_pads {
>   * @formats_list_size:	size of formats_list array
>   * @pads:		media controller pads for isc video entity
>   * @mdev:		media device that is registered by the isc
> + * @mpipe:		media device pipeline used by the isc
>   * @remote_pad:		remote pad on the connected subdevice
>   * @scaler_sd:		subdevice for the scaler that isc registers
>   * @scaler_pads:	media controller pads for the scaler subdevice
> @@ -295,6 +296,7 @@ struct isc_device {
>  	struct completion	comp;
>
>  	struct v4l2_format	fmt;
> +	struct v4l2_format	try_fmt;
>  	struct isc_format	**user_formats;
>  	unsigned int		num_user_formats;
>
> @@ -366,6 +368,7 @@ struct isc_device {
>  	struct {
>  		struct media_pad		pads[ISC_PADS_NUM];
>  		struct media_device		mdev;
> +		struct media_pipeline		mpipe;
>
>  		u32				remote_pad;
>  	};
> --
> 2.25.1
>