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Date:   Wed, 6 Oct 2021 23:28:26 +0300
From:   Sakari Ailus <sakari.ailus@linux.intel.com>
To:     Pratyush Yadav <p.yadav@ti.com>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Nikhil Devshatwar <nikhil.nd@ti.com>,
        Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Benoit Parrot <bparrot@ti.com>,
        Maxime Ripard <mripard@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Niklas =?iso-8859-1?Q?S=F6derlund?= 
        <niklas.soderlund+renesas@ragnatech.se>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-media@vger.kernel.org
Subject: Re: [PATCH v4 08/11] media: ti: Add CSI2RX support for J721E
Message-ID: <YV4G6kjCLREpbam2@paasikivi.fi.intel.com>
References: <20210915120240.21572-1-p.yadav@ti.com>
 <20210915120240.21572-9-p.yadav@ti.com>
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In-Reply-To: <20210915120240.21572-9-p.yadav@ti.com>
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Hi Pratyush,

On Wed, Sep 15, 2021 at 05:32:37PM +0530, Pratyush Yadav wrote:
...
> +/*
> + * Find the input format. This is done by finding the first device in the
> + * pipeline which can tell us the current format. This could be the sensor, or
> + * this could be another device in the middle which is capable of format
> + * conversions.
> + */
> +static int ti_csi2rx_validate_pipeline(struct ti_csi2rx_dev *csi)
> +{
> +	struct media_pipeline *pipe = &csi->pipe;
> +	struct media_entity *entity;
> +	struct v4l2_subdev *sd;
> +	struct v4l2_subdev_format fmt;
> +	struct v4l2_pix_format *pix = &csi->v_fmt.fmt.pix;
> +	struct media_device *mdev = &csi->mdev;
> +	const struct ti_csi2rx_fmt *ti_fmt;
> +	int ret;
> +
> +	mutex_lock(&mdev->graph_mutex);
> +	ret = media_graph_walk_init(&pipe->graph, mdev);
> +	if (ret) {
> +		mutex_unlock(&mdev->graph_mutex);
> +		return ret;
> +	}
> +
> +	media_graph_walk_start(&pipe->graph, &csi->vdev.entity);
> +
> +	while ((entity = media_graph_walk_next(&pipe->graph))) {
> +		if (!is_media_entity_v4l2_subdev(entity))
> +			continue;

You shouldn't rely on media_graph_walk_next() to return entities in a
particular order.

I'd suggest approach taken in isp_video_check_external_subdevs() (in
drivers/media/platform/omap3isp/ispvideo.c).

> +
> +		sd = media_entity_to_v4l2_subdev(entity);
> +
> +		fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
> +		fmt.pad = media_get_pad_index(entity, 0, PAD_SIGNAL_DEFAULT);
> +
> +		ret = v4l2_subdev_call(sd, pad, get_fmt, NULL, &fmt);
> +		if (ret && ret != -ENOIOCTLCMD) {
> +			media_graph_walk_cleanup(&pipe->graph);
> +			mutex_unlock(&mdev->graph_mutex);
> +			return ret;
> +		}
> +
> +		if (!ret)
> +			break;
> +	}
> +
> +	media_graph_walk_cleanup(&pipe->graph);
> +	mutex_unlock(&mdev->graph_mutex);
> +
> +	/* Could not find input format. */
> +	if (!entity)
> +		return -EPIPE;
> +
> +	if (fmt.format.width != pix->width)
> +		return -EPIPE;
> +	if (fmt.format.height != pix->height)
> +		return -EPIPE;

Pipeline validation should take place during media_pipeline_start(). Why
are you doing it here?

> +
> +	ti_fmt = find_format_by_pix(pix->pixelformat);
> +	if (WARN_ON(!ti_fmt))
> +		return -EINVAL;
> +
> +	if (fmt.format.code == MEDIA_BUS_FMT_YUYV8_2X8 ||
> +	    fmt.format.code == MEDIA_BUS_FMT_VYUY8_2X8 ||
> +	    fmt.format.code == MEDIA_BUS_FMT_YVYU8_2X8) {
> +		dev_err(csi->dev,
> +			"Only UYVY input allowed for YUV422 8-bit. Output format can be configured.\n");
> +		return -EPIPE;
> +	}
> +
> +	if (fmt.format.code == MEDIA_BUS_FMT_UYVY8_2X8) {
> +		/* Format conversion between YUV422 formats can be done. */
> +		if (ti_fmt->code != MEDIA_BUS_FMT_UYVY8_2X8 &&
> +		    ti_fmt->code != MEDIA_BUS_FMT_YUYV8_2X8 &&
> +		    ti_fmt->code != MEDIA_BUS_FMT_VYUY8_2X8 &&
> +		    ti_fmt->code != MEDIA_BUS_FMT_YVYU8_2X8)
> +			return -EPIPE;
> +	} else if (fmt.format.code != ti_fmt->code) {
> +		return -EPIPE;
> +	}
> +
> +	if (fmt.format.field != V4L2_FIELD_NONE &&
> +	    fmt.format.field != V4L2_FIELD_ANY)
> +		return -EPIPE;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	struct ti_csi2rx_buffer *buf, *tmp;
> +	unsigned long flags = 0;

No need to assign flags here.

> +	int ret = 0;
> +

-- 
Kind regards,

Sakari Ailus