Message-ID: <222dc5a1-6a12-4686-a065-39874d1e8f99@ti.com>
Date: Sat, 3 May 2025 11:24:57 +0530
From: Rishikesh Donadkar <r-donadkar@...com>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC: <jai.luthra@...ux.dev>, <mripard@...nel.org>,
        <linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <devarsht@...com>,
        <y-abhilashchandra@...com>, <mchehab@...nel.org>, <robh@...nel.org>,
        <krzk+dt@...nel.org>, <conor+dt@...nel.org>, <vaishnav.a@...com>,
        <s-jain1@...com>, <vigneshr@...com>, <sakari.ailus@...ux.intel.com>,
        <hverkuil-cisco@...all.nl>, <tomi.valkeinen@...asonboard.com>,
        <jai.luthra@...asonboard.com>, <changhuang.liang@...rfivetech.com>,
        <jack.zhu@...rfivetech.com>
Subject: Re: [PATCH v3 05/13] media: ti: j721e-csi2rx: add a subdev for the
 core device


On 21/04/25 18:42, Laurent Pinchart wrote:
> Hi Rishikesh,
>
> Thank you for the patch.


Hi Laurent,

Thank you for the review


>
> On Thu, Apr 17, 2025 at 12:25:46PM +0530, Rishikesh Donadkar wrote:
>> From: Jai Luthra <j-luthra@...com>
>>
>> With single stream capture, it was simpler to use the video device as
>> the media entity representing the main TI CSI2RX device. Now with multi
>> stream capture coming into the picture, the model has shifted to each
>> video device having a link to the main device's subdev. The routing
>> would then be set on this subdev.
>>
>> Add this subdev, link each context to this subdev's entity and link the
>> subdev's entity to the source. Also add an array of media pads. It will
>> have one sink pad and source pads equal to the number of contexts.
>>
>> Co-developed-by: Pratyush Yadav <p.yadav@...com>
>> Signed-off-by: Pratyush Yadav <p.yadav@...com>
>> Signed-off-by: Jai Luthra <j-luthra@...com>
>> Signed-off-by: Rishikesh Donadkar <r-donadkar@...com>
>> ---
>>   .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 230 ++++++++++++++++--
>>   1 file changed, 205 insertions(+), 25 deletions(-)
>>
>> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> index 523c890139098..ea7e331e872af 100644
>> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> @@ -51,6 +51,11 @@
>>   #define MAX_WIDTH_BYTES			SZ_16K
>>   #define MAX_HEIGHT_LINES		SZ_16K
>>   
>> +#define TI_CSI2RX_PAD_SINK		0
>> +#define TI_CSI2RX_PAD_FIRST_SOURCE	1
>> +#define TI_CSI2RX_NUM_SOURCE_PADS	1
>> +#define TI_CSI2RX_NUM_PADS		(1 + TI_CSI2RX_NUM_SOURCE_PADS)
>> +
>>   #define DRAIN_TIMEOUT_MS		50
>>   #define DRAIN_BUFFER_SIZE		SZ_32K
>>   
>> @@ -97,6 +102,7 @@ struct ti_csi2rx_ctx {
>>   	struct mutex			mutex; /* To serialize ioctls. */
>>   	struct v4l2_format		v_fmt;
>>   	struct ti_csi2rx_dma		dma;
>> +	struct media_pad		pad;
>>   	u32				sequence;
>>   	u32				idx;
>>   };
>> @@ -104,12 +110,15 @@ struct ti_csi2rx_ctx {
>>   struct ti_csi2rx_dev {
>>   	struct device			*dev;
>>   	void __iomem			*shim;
>> +	struct mutex			mutex; /* To serialize ioctls. */
>> +	unsigned int			enable_count;
>>   	struct v4l2_device		v4l2_dev;
>>   	struct media_device		mdev;
>>   	struct media_pipeline		pipe;
>> -	struct media_pad		pad;
>> +	struct media_pad		pads[TI_CSI2RX_NUM_PADS];
>>   	struct v4l2_async_notifier	notifier;
>>   	struct v4l2_subdev		*source;
>> +	struct v4l2_subdev		subdev;
>>   	struct ti_csi2rx_ctx		ctx[TI_CSI2RX_NUM_CTX];
>>   	/* Buffer to drain stale data from PSI-L endpoint */
>>   	struct {
>> @@ -431,6 +440,15 @@ static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
>>   	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
>>   	int ret, i;
>>   
>> +	/* Create link from source to subdev */
>> +	ret = v4l2_create_fwnode_links_to_pad(csi->source,
>> +					      &csi->pads[TI_CSI2RX_PAD_SINK],
>> +					      MEDIA_LNK_FL_IMMUTABLE |
>> +					      MEDIA_LNK_FL_ENABLED);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Create and link video nodes for all DMA contexts */
>>   	for (i = 0; i < TI_CSI2RX_NUM_CTX; i++) {
>>   		struct ti_csi2rx_ctx *ctx = &csi->ctx[i];
>>   		struct video_device *vdev = &ctx->vdev;
>> @@ -438,13 +456,17 @@ static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
>>   		ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
>>   		if (ret)
>>   			goto unregister_dev;
>> -	}
>>   
>> -	ret = v4l2_create_fwnode_links_to_pad(csi->source, &csi->pad,
>> -					      MEDIA_LNK_FL_IMMUTABLE |
>> -					      MEDIA_LNK_FL_ENABLED);
>> -	if (ret)
>> -		goto unregister_dev;
>> +		ret = media_create_pad_link(&csi->subdev.entity,
>> +					    TI_CSI2RX_PAD_FIRST_SOURCE + ctx->idx,
>> +					    &vdev->entity, 0,
>> +					    MEDIA_LNK_FL_IMMUTABLE |
>> +					    MEDIA_LNK_FL_ENABLED);
>> +		if (ret) {
>> +			video_unregister_device(vdev);
>> +			goto unregister_dev;
>> +		}
>> +	}
>>   
>>   	ret = v4l2_device_register_subdev_nodes(&csi->v4l2_dev);
>>   	if (ret)
>> @@ -454,8 +476,10 @@ static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
>>   
>>   unregister_dev:
>>   	i--;
>> -	for (; i >= 0; i--)
>> +	for (; i >= 0; i--) {
>> +		media_entity_remove_links(&csi->ctx[i].vdev.entity);
>>   		video_unregister_device(&csi->ctx[i].vdev);
>> +	}
>>   	return ret;
>>   }
>>   
>> @@ -859,7 +883,7 @@ static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>>   	dma->state = TI_CSI2RX_DMA_ACTIVE;
>>   	spin_unlock_irqrestore(&dma->lock, flags);
>>   
>> -	ret = v4l2_subdev_call(csi->source, video, s_stream, 1);
>> +	ret = v4l2_subdev_call(&csi->subdev, video, s_stream, 1);
>>   	if (ret)
>>   		goto err_dma;
>>   
>> @@ -887,7 +911,7 @@ static void ti_csi2rx_stop_streaming(struct vb2_queue *vq)
>>   	writel(0, csi->shim + SHIM_CNTL);
>>   	writel(0, csi->shim + SHIM_DMACNTX(ctx->idx));
>>   
>> -	ret = v4l2_subdev_call(csi->source, video, s_stream, 0);
>> +	ret = v4l2_subdev_call(&csi->subdev, video, s_stream, 0);
>>   	if (ret)
>>   		dev_err(csi->dev, "Failed to stop subdev stream\n");
>>   
>> @@ -903,8 +927,112 @@ static const struct vb2_ops csi_vb2_qops = {
>>   	.stop_streaming = ti_csi2rx_stop_streaming,
>>   };
>>   
>> +static inline struct ti_csi2rx_dev *to_csi2rx_dev(struct v4l2_subdev *sd)
>> +{
>> +	return container_of(sd, struct ti_csi2rx_dev, subdev);
>> +}
>> +
> It's customary to place such functions just after the definition of the
> corresponding structure.


Thanks, Will move it in the next revision.


>
>> +static int ti_csi2rx_sd_set_fmt(struct v4l2_subdev *sd,
>> +				struct v4l2_subdev_state *state,
>> +				struct v4l2_subdev_format *format)
>> +{
>> +	struct v4l2_mbus_framefmt *fmt;
>> +
>> +	/* No transcoding, don't allow setting source fmt */
>> +	if (format->pad > TI_CSI2RX_PAD_SINK)
>> +		return v4l2_subdev_get_fmt(sd, state, format);
>> +
>> +	if (!find_format_by_code(format->format.code))
>> +		format->format.code = ti_csi2rx_formats[0].code;
>> +
> Are there no minimum/maximum limits on the side ?


Are you suggesting that same limits as done in ti_csi2rx_fill_fmt()

should be imposed on the width and height?


>
>> +	format->format.field = V4L2_FIELD_NONE;
> The colorspace fields need handling too. It's typical for userspace to
> set them to *_DEFAULT, on the sink pad, and the kernel is supposed then
> adjust them as the V4L2 spec indicates that *_DEFAULT can't be returned.
>
> As lots of drivers handle color spaces in a pass-through way, some help
> from the V4L2 core would be nice.


Yes, that would be good to have.


>
>> +
>> +	fmt = v4l2_subdev_state_get_format(state, format->pad, format->stream);
>> +	*fmt = format->format;
>> +
>> +	fmt = v4l2_subdev_state_get_format(state, TI_CSI2RX_PAD_FIRST_SOURCE,
>> +					   format->stream);
>> +	*fmt = format->format;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ti_csi2rx_sd_init_state(struct v4l2_subdev *sd,
>> +				   struct v4l2_subdev_state *state)
>> +{
>> +	struct v4l2_subdev_format format = {
>> +		.pad = TI_CSI2RX_PAD_SINK,
>> +		.format = {
>> +			.width = 640,
>> +			.height = 480,
>> +			.code = MEDIA_BUS_FMT_UYVY8_1X16,
>> +			.field = V4L2_FIELD_NONE,
>> +			.colorspace = V4L2_COLORSPACE_SRGB,
>> +			.ycbcr_enc = V4L2_YCBCR_ENC_601,
>> +			.quantization = V4L2_QUANTIZATION_LIM_RANGE,
>> +			.xfer_func = V4L2_XFER_FUNC_SRGB,
>> +		},
>> +	};
>> +
>> +	return ti_csi2rx_sd_set_fmt(sd, state, &format);
> Given that ti_csi2rx_sd_set_fmt() doesn't really perform any relevant
> adjustment for the default format, it may be easier to replace the above
> structure with a static const struct v4l2_mbus_framefmt, and assign it
> to the sink and source formats. It depends a bit on how
> ti_csi2rx_sd_set_fmt() will evolve when adding support for multiple
> streams.


Right, I will make the changes here to have bisectability. But, the body of

this function will change in [PATCH v3 11/13] of this series.


>
>> +}
>> +
>> +static int ti_csi2rx_sd_s_stream(struct v4l2_subdev *sd, int enable)
>> +{
>> +	struct ti_csi2rx_dev *csi = to_csi2rx_dev(sd);
>> +	int ret = 0;
>> +
>> +	mutex_lock(&csi->mutex);
>> +
>> +	if (enable) {
>> +		if (csi->enable_count > 0) {
>> +			csi->enable_count++;
>> +			goto out;
>> +		}
>> +
>> +		ret = v4l2_subdev_call(csi->source, video, s_stream, 1);
>> +		if (ret)
>> +			goto out;
>> +
>> +		csi->enable_count++;
>> +	} else {
>> +		if (csi->enable_count == 0) {
>> +			ret = -EINVAL;
>> +			goto out;
>> +		}
>> +
>> +		if (--csi->enable_count > 0)
>> +			goto out;
>> +
>> +		ret = v4l2_subdev_call(csi->source, video, s_stream, 0);
>> +	}
>> +
>> +out:
>> +	mutex_unlock(&csi->mutex);
>> +	return ret;
>> +}
>> +
>> +static const struct v4l2_subdev_pad_ops ti_csi2rx_subdev_pad_ops = {
> Have you run v4l2-compliance ? I would have thought that at least
> .enum_mbus_code would be mandatory.


Thanks for pointing out, Will add.


>
>> +	.get_fmt = v4l2_subdev_get_fmt,
>> +	.set_fmt = ti_csi2rx_sd_set_fmt,
>> +};
>> +
>> +static const struct v4l2_subdev_video_ops ti_csi2rx_subdev_video_ops = {
>> +	.s_stream = ti_csi2rx_sd_s_stream,
>> +};
>> +
>> +static const struct v4l2_subdev_ops ti_csi2rx_subdev_ops = {
>> +	.video = &ti_csi2rx_subdev_video_ops,
>> +	.pad = &ti_csi2rx_subdev_pad_ops,
>> +};
>> +
>> +static const struct v4l2_subdev_internal_ops ti_csi2rx_internal_ops = {
>> +	.init_state = ti_csi2rx_sd_init_state,
>> +};
>> +
>>   static void ti_csi2rx_cleanup_v4l2(struct ti_csi2rx_dev *csi)
>>   {
>> +	v4l2_subdev_cleanup(&csi->subdev);
>>   	media_device_unregister(&csi->mdev);
>>   	v4l2_device_unregister(&csi->v4l2_dev);
>>   	media_device_cleanup(&csi->mdev);
>> @@ -961,14 +1089,22 @@ static int ti_csi2rx_link_validate(struct media_link *link)
>>   	struct v4l2_subdev_format source_fmt = {
>>   		.which	= V4L2_SUBDEV_FORMAT_ACTIVE,
>>   		.pad	= link->source->index,
>> +		.stream = 0,
>>   	};
>> +	struct v4l2_subdev_state *state;
>>   	const struct ti_csi2rx_fmt *ti_fmt;
>>   	int ret;
>>   
>> -	ret = v4l2_subdev_call_state_active(csi->source, pad,
>> -					    get_fmt, &source_fmt);
>> -	if (ret)
>> -		return ret;
>> +	state = v4l2_subdev_lock_and_get_active_state(&csi->subdev);
>> +	ret = v4l2_subdev_call(&csi->subdev, pad, get_fmt, state, &source_fmt);
>> +	v4l2_subdev_unlock_state(state);
>> +
>> +	if (ret) {
>> +		dev_dbg(csi->dev,
>> +			"Skipping validation as no format present on \"%s\":%u:0\n",
>> +			link->source->entity->name, link->source->index);
> How can no format be present ? Is this for the case where no stream is
> routed to a particular context ? If so, the corresponding video device
> shouldn't be reached by the pipeline walk algorithm, and this function
> shouldn't be called in the first place. Am I missing something ?


In this driver we keep all the links enabled and immutable by default.

If no streams are routed to a particular context (i.e the pad is 
unused), it wont have

the formats set, in that case we skip validation and return 0. This is 
done so that streaming from a context

for which routes and format has been set does not fail..


>
>> +		return 0;
>> +	}
>>   
>>   	if (source_fmt.format.width != csi_fmt->width) {
>>   		dev_dbg(csi->dev, "Width does not match (source %u, sink %u)\n",
>> @@ -998,8 +1134,9 @@ static int ti_csi2rx_link_validate(struct media_link *link)
>>   
>>   	if (ti_fmt->fourcc != csi_fmt->pixelformat) {
>>   		dev_dbg(csi->dev,
>> -			"Cannot transform source fmt 0x%x to sink fmt 0x%x\n",
>> -			ti_fmt->fourcc, csi_fmt->pixelformat);
>> +			"Cannot transform \"%s\":%u format %p4cc to %p4cc\n",
>> +			link->source->entity->name, link->source->index,
>> +			&ti_fmt->fourcc, &csi_fmt->pixelformat);
>>   		return -EPIPE;
>>   	}
>>   
>> @@ -1010,6 +1147,10 @@ static const struct media_entity_operations ti_csi2rx_video_entity_ops = {
>>   	.link_validate = ti_csi2rx_link_validate,
>>   };
>>   
>> +static const struct media_entity_operations ti_csi2rx_subdev_entity_ops = {
>> +	.link_validate = v4l2_subdev_link_validate,
>> +};
>> +
>>   static int ti_csi2rx_init_dma(struct ti_csi2rx_ctx *ctx)
>>   {
>>   	struct dma_slave_config cfg = {
>> @@ -1041,6 +1182,7 @@ static int ti_csi2rx_init_dma(struct ti_csi2rx_ctx *ctx)
>>   static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
>>   {
>>   	struct media_device *mdev = &csi->mdev;
>> +	struct v4l2_subdev *sd = &csi->subdev;
>>   	int ret;
>>   
>>   	mdev->dev = csi->dev;
>> @@ -1053,16 +1195,51 @@ static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
>>   
>>   	ret = v4l2_device_register(csi->dev, &csi->v4l2_dev);
>>   	if (ret)
>> -		return ret;
>> +		goto cleanup_media;
>>   
>>   	ret = media_device_register(mdev);
>> -	if (ret) {
>> -		v4l2_device_unregister(&csi->v4l2_dev);
>> -		media_device_cleanup(mdev);
>> -		return ret;
>> -	}
>> +	if (ret)
>> +		goto unregister_v4l2;
>> +
>> +	v4l2_subdev_init(sd, &ti_csi2rx_subdev_ops);
>> +	sd->internal_ops = &ti_csi2rx_internal_ops;
>> +	sd->entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
>> +	sd->flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
>> +	strscpy(sd->name, dev_name(csi->dev), sizeof(sd->name));
>> +	sd->dev = csi->dev;
>> +	sd->entity.ops = &ti_csi2rx_subdev_entity_ops;
>> +
>> +	csi->pads[TI_CSI2RX_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
>> +
>> +	for (unsigned int i = TI_CSI2RX_PAD_FIRST_SOURCE;
>> +	     i < TI_CSI2RX_NUM_PADS; i++)
>> +		csi->pads[i].flags = MEDIA_PAD_FL_SOURCE;
>> +
>> +	ret = media_entity_pads_init(&sd->entity, ARRAY_SIZE(csi->pads),
>> +				     csi->pads);
>> +	if (ret)
>> +		goto unregister_media;
>> +
>> +	ret = v4l2_subdev_init_finalize(sd);
>> +	if (ret)
>> +		goto unregister_media;
>> +
>> +	ret = v4l2_device_register_subdev(&csi->v4l2_dev, sd);
>> +	if (ret)
>> +		goto cleanup_subdev;
>>   
>>   	return 0;
>> +
>> +cleanup_subdev:
>> +	v4l2_subdev_cleanup(sd);
>> +unregister_media:
>> +	media_device_unregister(mdev);
>> +unregister_v4l2:
>> +	v4l2_device_unregister(&csi->v4l2_dev);
>> +cleanup_media:
>> +	media_device_cleanup(mdev);
>> +
>> +	return ret;
>>   }
>>   
>>   static int ti_csi2rx_init_ctx(struct ti_csi2rx_ctx *ctx)
>> @@ -1089,9 +1266,9 @@ static int ti_csi2rx_init_ctx(struct ti_csi2rx_ctx *ctx)
>>   
>>   	ti_csi2rx_fill_fmt(fmt, &ctx->v_fmt);
>>   
>> -	csi->pad.flags = MEDIA_PAD_FL_SINK;
>> +	ctx->pad.flags = MEDIA_PAD_FL_SINK;
>>   	vdev->entity.ops = &ti_csi2rx_video_entity_ops;
>> -	ret = media_entity_pads_init(&ctx->vdev.entity, 1, &csi->pad);
>> +	ret = media_entity_pads_init(&ctx->vdev.entity, 1, &ctx->pad);
>>   	if (ret)
>>   		return ret;
>>   
>> @@ -1147,6 +1324,8 @@ static int ti_csi2rx_probe(struct platform_device *pdev)
>>   	if (!csi->drain.vaddr)
>>   		return -ENOMEM;
>>   
>> +	mutex_init(&csi->mutex);
>> +
>>   	ret = ti_csi2rx_v4l2_init(csi);
>>   	if (ret)
>>   		goto err_v4l2;
>> @@ -1179,6 +1358,7 @@ static int ti_csi2rx_probe(struct platform_device *pdev)
>>   		ti_csi2rx_cleanup_ctx(&csi->ctx[i]);
>>   	ti_csi2rx_cleanup_v4l2(csi);
>>   err_v4l2:
>> +	mutex_destroy(&csi->mutex);
>>   	dma_free_coherent(csi->dev, csi->drain.len, csi->drain.vaddr,
>>   			  csi->drain.paddr);
>>   	return ret;
>> @@ -1194,7 +1374,7 @@ static void ti_csi2rx_remove(struct platform_device *pdev)
>>   
>>   	ti_csi2rx_cleanup_notifier(csi);
>>   	ti_csi2rx_cleanup_v4l2(csi);
>> -
>> +	mutex_destroy(&csi->mutex);
>>   	dma_free_coherent(csi->dev, csi->drain.len, csi->drain.vaddr,
>>   			  csi->drain.paddr);
>>   }

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