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Message-ID: <719ee15a-92fd-4597-b25e-196f4a906a5a@ti.com>
Date: Tue, 9 Dec 2025 15:38:33 +0530
From: Rishikesh Donadkar <r-donadkar@...com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, <jai.luthra@...ux.dev>,
<laurent.pinchart@...asonboard.com>, <mripard@...nel.org>
CC: <y-abhilashchandra@...com>, <devarsht@...com>, <s-jain1@...com>,
<vigneshr@...com>, <mchehab@...nel.org>, <robh@...nel.org>,
<krzk+dt@...nel.org>, <p.zabel@...gutronix.de>, <conor+dt@...nel.org>,
<sakari.ailus@...ux.intel.com>, <hverkuil-cisco@...all.nl>,
<jai.luthra@...asonboard.com>, <changhuang.liang@...rfivetech.com>,
<jack.zhu@...rfivetech.com>, <sjoerd@...labora.com>,
<dan.carpenter@...aro.org>, <hverkuil+cisco@...nel.org>,
<linux-kernel@...r.kernel.org>, <linux-media@...r.kernel.org>,
<devicetree@...r.kernel.org>
Subject: Re: [PATCH v8 13/18] media: ti: j721e-csi2rx: add multistream support
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@...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@...com>
>> Co-developed-by: Pratyush Yadav <p.yadav@...com>
>> Signed-off-by: Pratyush Yadav <p.yadav@...com>
>> Signed-off-by: Jai Luthra <j-luthra@...com>
>> Co-developed-by: Rishikesh Donadkar <r-donadkar@...com>
>> Signed-off-by: Rishikesh Donadkar <r-donadkar@...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);
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