Re: [PATCH v8 13/18] media: ti: j721e-csi2rx: add multistream support

[Rishikesh Donadkar <r-donadkar@ti.com>]

On 01/12/25 18:33, Tomi Valkeinen wrote:
> Hi,


Hi Tomi,

Thank you for the review !

>
> On 12/11/2025 13:54, Rishikesh Donadkar wrote:
>> From: Jai Luthra <j-luthra@ti.com>
>>
>> Each CSI2 stream can be multiplexed into 4 independent streams, each
> Well, that's not true, at least generally speaking (there can be more
> than 4). Is that specific to TI hardware?


Yes, The commit message talks about how TI CSI does the multiplexing of 
CSI stream from the sensor into 4 streams as show in the Figure 12-388 
in AM62A TRM[1]. I will modify the commit message to mention that this 
is TI CSI specific.


[1]: 
https://www.ti.com/lit/ug/spruj16c/spruj16c.pdf?ts=1765273774405&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FAM62A7


>
>> identified by its virtual channel number and data type. The incoming
>> data from these streams can be filtered on the basis of either the
>> virtual channel or the data type.
>>
>> To capture this multiplexed stream, the application needs to tell
>> the driver how it wants to route the data. It needs to specify
>> which context should process which stream. This is done via the
>> new routing APIs.
>>
>> Add ioctls to accept routing information from the application and save
>> that in the driver. This can be used when starting streaming on a
>> context to determine which route and consequently which virtual channel
>> it should process.
>>
>> De-assert the pixel interface reset on first start_streaming() and assert
>> it on the last stop_streaming().
>>
>> Reviewed-by: Yemike Abhilash Chandra <y-abhilashchandra@ti.com>
>> Co-developed-by: Pratyush Yadav <p.yadav@ti.com>
>> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
>> Signed-off-by: Jai Luthra <j-luthra@ti.com>
>> Co-developed-by: Rishikesh Donadkar <r-donadkar@ti.com>
>> Signed-off-by: Rishikesh Donadkar <r-donadkar@ti.com>
>> ---
>>   .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 224 ++++++++++++++----
>>   1 file changed, 179 insertions(+), 45 deletions(-)
>>
>> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> index 126a62fa2c4c4..c8e0e761f2802 100644
>> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
>> @@ -103,6 +103,7 @@ struct ti_csi2rx_dev;
>>   
>>   struct ti_csi2rx_ctx {
>>   	struct ti_csi2rx_dev		*csi;
>> +	struct v4l2_subdev_route        *route;
>>   	struct video_device		vdev;
>>   	struct vb2_queue		vidq;
>>   	struct mutex			mutex; /* To serialize ioctls. */
>> @@ -136,6 +137,7 @@ struct ti_csi2rx_dev {
>>   		dma_addr_t		paddr;
>>   		size_t			len;
>>   	} drain;
>> +	bool                            vc_cached;
>>   };
>>   
>>   static inline struct ti_csi2rx_dev *to_csi2rx_dev(struct v4l2_subdev *sd)
>> @@ -143,17 +145,6 @@ static inline struct ti_csi2rx_dev *to_csi2rx_dev(struct v4l2_subdev *sd)
>>   	return container_of(sd, struct ti_csi2rx_dev, subdev);
>>   }
>>   
>> -static const struct v4l2_mbus_framefmt ti_csi2rx_default_fmt = {
>> -	.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,
>> -};
>> -
>>   static const struct ti_csi2rx_fmt ti_csi2rx_formats[] = {
>>   	{
>>   		.fourcc			= V4L2_PIX_FMT_YUYV,
>> @@ -566,8 +557,10 @@ static void ti_csi2rx_setup_shim(struct ti_csi2rx_ctx *ctx)
>>   	fmt = find_format_by_fourcc(ctx->v_fmt.fmt.pix.pixelformat);
>>   
>>   	/* De-assert the pixel interface reset. */
>> -	reg = SHIM_CNTL_PIX_RST;
>> -	writel(reg, csi->shim + SHIM_CNTL);
>> +	if (!csi->enable_count) {
>> +		reg = SHIM_CNTL_PIX_RST;
>> +		writel(reg, csi->shim + SHIM_CNTL);
>> +	}
>>   
>>   	/* Negotiate pixel count from the source */
>>   	ti_csi2rx_request_max_ppc(csi);
>> @@ -888,30 +881,80 @@ static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
>>   	}
>>   }
>>   
>> +static int ti_csi2rx_get_route(struct ti_csi2rx_ctx *ctx)
>> +{
>> +	struct ti_csi2rx_dev *csi = ctx->csi;
>> +	struct media_pad *pad;
>> +	struct v4l2_subdev_state *state;
>> +	struct v4l2_subdev_route *r;
>> +
>> +	/* Get the source pad connected to this ctx */
>> +	pad = media_entity_remote_source_pad_unique(ctx->pad.entity);
>> +	if (!pad) {
>> +		dev_err(csi->dev, "No pad connected to ctx %d\n", ctx->idx);
>> +		return -ENODEV;
>> +	}
>> +
>> +	state = v4l2_subdev_lock_and_get_active_state(&csi->subdev);
> This looks a bit concerning. You lock the state, find the correct route
> and store a pointer to the route into the ctx, then unlock the state...
> Alarm bells should be ringing here.


Thank you for pointing out, I will store the stream number instead of 
storing the pointer for route, here we don't allow anyone to update the 
routes when we are in streaming (i.e. if csi->enable_count > 0, return 
-EBUSY). So, the stream number is not likely to change.

>
>> +
>> +	for_each_active_route(&state->routing, r) {
>> +		if (!(r->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
> for_each_active_route() already checks this ("_active_").


Okay, I will remove the check for active route.

>
>> +			continue;
>> +		if (r->source_pad != pad->index)
>> +			continue;
>> +
>> +		ctx->route = r;
> Shouldn't you break here?


Right, I will add a break here

>
>> +	}
>> +
>> +	v4l2_subdev_unlock_state(state);
>> +
>> +	if (!ctx->route)
>> +		return -ENODEV;
>> +
>> +	return 0;
>> +}
>> +
>>   static int ti_csi2rx_get_vc(struct ti_csi2rx_ctx *ctx)
>>   {
>>   	struct ti_csi2rx_dev *csi = ctx->csi;
>> +	struct ti_csi2rx_ctx *curr_ctx;
>>   	struct v4l2_mbus_frame_desc fd;
>> -	struct media_pad *pad;
>> -	int ret, i;
>> +	struct media_pad *source_pad;
>> +	struct v4l2_subdev_route *curr_route;
>> +	int ret;
>> +	unsigned int i, j;
>>   
>> -	pad = media_entity_remote_pad_unique(&csi->subdev.entity, MEDIA_PAD_FL_SOURCE);
>> -	if (!pad)
>> +	/* Get the frame desc form source */
>> +	source_pad = media_entity_remote_pad_unique(&csi->subdev.entity, MEDIA_PAD_FL_SOURCE);
>> +	if (!source_pad)
>>   		return -ENODEV;
>>   
>> -	ret = v4l2_subdev_call(csi->source, pad, get_frame_desc, pad->index, &fd);
>> +	ret = v4l2_subdev_call(csi->source, pad, get_frame_desc, source_pad->index, &fd);
>>   	if (ret)
>>   		return ret;
>>   
>>   	if (fd.type != V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
>>   		return -EINVAL;
>>   
>> -	for (i = 0; i < fd.num_entries; i++) {
>> -		if (ctx->stream == fd.entry[i].stream)
>> -			return fd.entry[i].bus.csi2.vc;
>> +	for (i = 0; i < csi->num_ctx; i++) {
>> +		curr_ctx = &csi->ctx[i];
>> +
>> +		/* Capture VC 0 by default */
>> +		curr_ctx->vc = 0;
>> +
>> +		ret = ti_csi2rx_get_route(curr_ctx);
>> +		if (ret)
>> +			continue;
>> +
>> +		curr_route = curr_ctx->route;
>> +		curr_ctx->stream = curr_route->sink_stream;
>> +
>> +		for (j = 0; j < fd.num_entries; j++)
>> +			if (curr_ctx->stream == fd.entry[j].stream)
>> +				curr_ctx->vc = fd.entry[j].bus.csi2.vc;
>>   	}
>>   
>> -	return -ENODEV;
>> +	return 0;
>>   }
>>   
>>   static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>> @@ -934,13 +977,24 @@ static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>>   	if (ret)
>>   		goto err;
>>   
>> -	ret = ti_csi2rx_get_vc(ctx);
>> -	if (ret == -ENOIOCTLCMD)
>> -		ctx->vc = 0;
>> -	else if (ret < 0)
>> +	/* If no stream is routed to this ctx, exit early */
>> +	ret = ti_csi2rx_get_route(ctx);
>> +	if (ret)
>>   		goto err;
>> -	else
>> -		ctx->vc = ret;
>> +
>> +	/* Get the VC for all enabled ctx on first stream start */
> Is the comment right? How does this work? ti_csi2rx_get_vc() is passed a
> single context, but... it gets VCs for all contexts? And shouldn't these
> also be dealing with DT at the same time with VC?


Yes, here we pass a single context to ti_csi2rx_get_vc(), but we loop 
over all the ctx on first stream start.

I will modify this function to also deal with DT.

>
>> +	mutex_lock(&csi->mutex);
>> +	if (!csi->vc_cached) {
>> +		ret = ti_csi2rx_get_vc(ctx);
>> +		if (ret == -ENOIOCTLCMD) {
>> +			ctx->vc = 0;
>> +		} else if (ret < 0) {
>> +			mutex_unlock(&csi->mutex);
>> +			goto err;
>> +		}
>> +		csi->vc_cached = true;
>> +	}
>> +	mutex_unlock(&csi->mutex);
>>   
>>   	ti_csi2rx_setup_shim(ctx);
>>   
>> @@ -960,8 +1014,9 @@ 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);
>>   
>> +	/* Start stream 0, we don't allow multiple streams on the source pad */
>>   	ret = v4l2_subdev_enable_streams(&csi->subdev,
>> -					 TI_CSI2RX_PAD_FIRST_SOURCE,
>> +					 TI_CSI2RX_PAD_FIRST_SOURCE + ctx->idx,
>>   					 BIT(0));
>>   	if (ret)
>>   		goto err_dma;
>> @@ -985,17 +1040,26 @@ static void ti_csi2rx_stop_streaming(struct vb2_queue *vq)
>>   	struct ti_csi2rx_dev *csi = ctx->csi;
>>   	int ret;
>>   
>> -	video_device_pipeline_stop(&ctx->vdev);
>> +	mutex_lock(&csi->mutex);
>>   
>> -	writel(0, csi->shim + SHIM_CNTL);
>>   	writel(0, csi->shim + SHIM_DMACNTX(ctx->idx));
>>   
>> +	/* assert pixel reset to prevent stale data */
>> +	if (csi->enable_count == 1) {
>> +		writel(0, csi->shim + SHIM_CNTL);
>> +		csi->vc_cached = false;
>> +	}
>> +
>> +	video_device_pipeline_stop(&ctx->vdev);
>> +
>>   	ret = v4l2_subdev_disable_streams(&csi->subdev,
>> -					  TI_CSI2RX_PAD_FIRST_SOURCE,
>> +					  TI_CSI2RX_PAD_FIRST_SOURCE + ctx->idx,
>>   					  BIT(0));
>>   	if (ret)
>>   		dev_err(csi->dev, "Failed to stop subdev stream\n");
>>   
>> +	mutex_unlock(&csi->mutex);
>> +
>>   	ti_csi2rx_stop_dma(ctx);
>>   	ti_csi2rx_cleanup_buffers(ctx, VB2_BUF_STATE_ERROR);
>>   }
>> @@ -1038,25 +1102,84 @@ static int ti_csi2rx_sd_set_fmt(struct v4l2_subdev *sd,
>>   	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 = v4l2_subdev_state_get_opposite_stream_format(state, format->pad,
>> +							   format->stream);
>> +	if (!fmt)
>> +		return -EINVAL;
>> +
>>   	*fmt = format->format;
>>   
>>   	return 0;
>>   }
>>   
>> -static int ti_csi2rx_sd_init_state(struct v4l2_subdev *sd,
>> -				   struct v4l2_subdev_state *state)
>> +static int _ti_csi2rx_sd_set_routing(struct v4l2_subdev *sd,
>> +				     struct v4l2_subdev_state *state,
>> +				     struct v4l2_subdev_krouting *routing)
>>   {
>> -	struct v4l2_mbus_framefmt *fmt;
>> +	int ret;
>>   
>> -	fmt = v4l2_subdev_state_get_format(state, TI_CSI2RX_PAD_SINK);
>> -	*fmt = ti_csi2rx_default_fmt;
>> +	const struct v4l2_mbus_framefmt format = {
> "static const"


Okay


Rishikesh

>
>> +		.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,
>> +	};
>>   
>> -	fmt = v4l2_subdev_state_get_format(state, TI_CSI2RX_PAD_FIRST_SOURCE);
>> -	*fmt = ti_csi2rx_default_fmt;
>> +	ret = v4l2_subdev_routing_validate(sd, routing,
>> +					   V4L2_SUBDEV_ROUTING_ONLY_1_TO_1 |
>> +					   V4L2_SUBDEV_ROUTING_NO_SOURCE_MULTIPLEXING);
>>   
>> -	return 0;
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Only stream ID 0 allowed on source pads */
>> +	for (unsigned int i = 0; i < routing->num_routes; ++i) {
>> +		const struct v4l2_subdev_route *route = &routing->routes[i];
>> +
>> +		if (route->source_stream != 0)
>> +			return -EINVAL;
>> +	}
>> +
>> +	ret = v4l2_subdev_set_routing_with_fmt(sd, state, routing, &format);
>> +
>> +	return ret;
>> +}
>> +
>> +static int ti_csi2rx_sd_set_routing(struct v4l2_subdev *sd,
>> +				    struct v4l2_subdev_state *state,
>> +				    enum v4l2_subdev_format_whence which,
>> +				    struct v4l2_subdev_krouting *routing)
>> +{
>> +	struct ti_csi2rx_dev *csi = to_csi2rx_dev(sd);
>> +
>> +	if (csi->enable_count > 0)
>> +		return -EBUSY;
>> +
>> +	return _ti_csi2rx_sd_set_routing(sd, state, routing);
>> +}
>> +
>> +static int ti_csi2rx_sd_init_state(struct v4l2_subdev *sd,
>> +				   struct v4l2_subdev_state *state)
>> +{
>> +	struct v4l2_subdev_route routes[] = { {
>> +		.sink_pad = 0,
>> +		.sink_stream = 0,
>> +		.source_pad = TI_CSI2RX_PAD_FIRST_SOURCE,
>> +		.source_stream = 0,
>> +		.flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE,
>> +	} };
>> +
>> +	struct v4l2_subdev_krouting routing = {
>> +		.num_routes = 1,
>> +		.routes = routes,
>> +	};
>> +
>> +	/* Initialize routing to single route to the fist source pad */
>> +	return _ti_csi2rx_sd_set_routing(sd, state, &routing);
>>   }
>>   
>>   static int ti_csi2rx_sd_enable_streams(struct v4l2_subdev *sd,
>> @@ -1065,14 +1188,18 @@ static int ti_csi2rx_sd_enable_streams(struct v4l2_subdev *sd,
>>   {
>>   	struct ti_csi2rx_dev *csi = to_csi2rx_dev(sd);
>>   	struct media_pad *remote_pad;
>> +	u64 sink_streams;
>>   	int ret = 0;
>>   
>>   	remote_pad = media_entity_remote_source_pad_unique(&csi->subdev.entity);
>>   	if (!remote_pad)
>>   		return -ENODEV;
>> +	sink_streams = v4l2_subdev_state_xlate_streams(state, pad,
>> +						       TI_CSI2RX_PAD_SINK,
>> +						       &streams_mask);
>>   
>>   	ret = v4l2_subdev_enable_streams(csi->source, remote_pad->index,
>> -					 BIT(0));
>> +					 sink_streams);
>>   	if (ret)
>>   		return ret;
>>   
>> @@ -1087,17 +1214,21 @@ static int ti_csi2rx_sd_disable_streams(struct v4l2_subdev *sd,
>>   {
>>   	struct ti_csi2rx_dev *csi = to_csi2rx_dev(sd);
>>   	struct media_pad *remote_pad;
>> +	u64 sink_streams;
>>   	int ret = 0;
>>   
>>   	remote_pad = media_entity_remote_source_pad_unique(&csi->subdev.entity);
>>   	if (!remote_pad)
>>   		return -ENODEV;
>> +	sink_streams = v4l2_subdev_state_xlate_streams(state, pad,
>> +						       TI_CSI2RX_PAD_SINK,
>> +						       &streams_mask);
>>   
>>   	if (csi->enable_count == 0)
>>   		return -EINVAL;
>>   
>>   	ret = v4l2_subdev_disable_streams(csi->source, remote_pad->index,
>> -					  BIT(0));
>> +					  sink_streams);
>>   	if (!ret)
>>   		--csi->enable_count;
>>   
>> @@ -1106,6 +1237,7 @@ static int ti_csi2rx_sd_disable_streams(struct v4l2_subdev *sd,
>>   
>>   static const struct v4l2_subdev_pad_ops ti_csi2rx_subdev_pad_ops = {
>>   	.enum_mbus_code	= ti_csi2rx_enum_mbus_code,
>> +	.set_routing = ti_csi2rx_sd_set_routing,
>>   	.get_fmt = v4l2_subdev_get_fmt,
>>   	.set_fmt = ti_csi2rx_sd_set_fmt,
>>   	.enable_streams = ti_csi2rx_sd_enable_streams,
>> @@ -1284,7 +1416,7 @@ static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
>>   	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;
>> +	sd->flags = V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_STREAMS;
>>   	strscpy(sd->name, dev_name(csi->dev), sizeof(sd->name));
>>   	sd->dev = csi->dev;
>>   	sd->entity.ops = &ti_csi2rx_subdev_entity_ops;
>> @@ -1347,6 +1479,8 @@ static int ti_csi2rx_init_ctx(struct ti_csi2rx_ctx *ctx)
>>   
>>   	ti_csi2rx_fill_fmt(fmt, &ctx->v_fmt);
>>   
>> +	ctx->route = NULL;
>> +
>>   	ctx->pad.flags = MEDIA_PAD_FL_SINK;
>>   	vdev->entity.ops = &ti_csi2rx_video_entity_ops;
>>   	ret = media_entity_pads_init(&ctx->vdev.entity, 1, &ctx->pad);