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Message-ID: <1029b7b3-44cf-4ed5-b90a-a476d39da5a8@ideasonboard.com>
Date: Thu, 15 Jan 2026 14:01:49 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Rishikesh Donadkar <r-donadkar@...com>
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, jai.luthra@...ux.dev,
laurent.pinchart@...asonboard.com, mripard@...nel.org
Subject: Re: [PATCH v9 12/19] media: cadence: csi2rx: add multistream support
Hi,
On 30/12/2025 10:32, Rishikesh Donadkar wrote:
> From: Jai Luthra <j-luthra@...com>
>
> Cadence CSI-2 bridge IP supports capturing multiple virtual "streams"
> of data over the same physical interface using MIPI Virtual Channels.
>
> While the hardware IP supports usecases where streams coming in the sink
> pad can be broadcasted to multiple source pads, the driver will need
> significant re-architecture to make that possible. The two users of this
> IP in mainline linux are TI Shim and StarFive JH7110 CAMSS, and both
> have only integrated the first source pad i.e stream0 of this IP. So for
> now keep it simple and only allow 1-to-1 mapping of streams from sink to
> source, without any broadcasting.
>
> Signed-off-by: Jai Luthra <j-luthra@...com>
> Reviewed-by: Changhuang Liang <changhuang.liang@...rfivetech.com>
> Reviewed-by: Yemike Abhilash Chandra <y-abhilashchandra@...com>
> Co-developed-by: Rishikesh Donadkar <r-donadkar@...com>
> Signed-off-by: Rishikesh Donadkar <r-donadkar@...com>
> ---
> drivers/media/platform/cadence/cdns-csi2rx.c | 248 +++++++++++++++----
> 1 file changed, 201 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index 65c6acb02f85b..5c16a2e509136 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -135,6 +135,7 @@ struct csi2rx_priv {
> struct phy *dphy;
>
> u8 num_pixels[CSI2RX_STREAMS_MAX];
> + u32 vc_select[CSI2RX_STREAMS_MAX];
> u8 lanes[CSI2RX_LANES_MAX];
> u8 num_lanes;
> u8 max_lanes;
> @@ -273,30 +274,43 @@ static void csi2rx_reset(struct csi2rx_priv *csi2rx)
>
> static int csi2rx_configure_ext_dphy(struct csi2rx_priv *csi2rx)
> {
> - struct media_pad *src_pad =
> - &csi2rx->source_subdev->entity.pads[csi2rx->source_pad];
> union phy_configure_opts opts = { };
> struct phy_configure_opts_mipi_dphy *cfg = &opts.mipi_dphy;
> - struct v4l2_subdev_state *state;
> struct v4l2_mbus_framefmt *framefmt;
> + struct v4l2_subdev_state *state;
> const struct csi2rx_fmt *fmt;
> + int source_pad = csi2rx->source_pad;
> + struct media_pad *pad = &csi2rx->source_subdev->entity.pads[source_pad];
> s64 link_freq;
> int ret;
> + u32 bpp;
>
> state = v4l2_subdev_get_locked_active_state(&csi2rx->subdev);
>
> - framefmt = v4l2_subdev_state_get_format(state, CSI2RX_PAD_SINK, 0);
> - if (!framefmt) {
> - dev_err(csi2rx->dev, "Did not find active sink format\n");
> - return -EINVAL;
> - }
> + /*
> + * For multi-stream transmitters there is no single pixel rate.
> + *
> + * In multistream usecase pass bpp as 0 so that v4l2_get_link_freq()
> + * returns an error if it falls back to V4L2_CID_PIXEL_RATE.
> + */
> + if (state->routing.num_routes > 1) {
> + bpp = 0;
> + } else {
> + framefmt = v4l2_subdev_state_get_format(state, CSI2RX_PAD_SINK, 0);
> + if (!framefmt) {
> + dev_err(csi2rx->dev, "Did not find active sink format\n");
> + return -EINVAL;
> + }
>
> - fmt = csi2rx_get_fmt_by_code(framefmt->code);
> + fmt = csi2rx_get_fmt_by_code(framefmt->code);
> + bpp = fmt->bpp;
> + }
>
> - link_freq = v4l2_get_link_freq(src_pad,
> - fmt->bpp, 2 * csi2rx->num_lanes);
> - if (link_freq < 0)
> + link_freq = v4l2_get_link_freq(pad, bpp, 2 * csi2rx->num_lanes);
> + if (link_freq < 0) {
> + dev_err(csi2rx->dev, "Unable to calculate link frequency\n");
> return link_freq;
> + }
>
> ret = phy_mipi_dphy_get_default_config_for_hsclk(link_freq,
> csi2rx->num_lanes, cfg);
> @@ -394,11 +408,7 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> csi2rx->num_pixels[i]),
> csi2rx->base + CSI2RX_STREAM_CFG_REG(i));
>
> - /*
> - * Enable one virtual channel. When multiple virtual channels
> - * are supported this will have to be changed.
> - */
> - writel(CSI2RX_STREAM_DATA_CFG_VC_SELECT(0),
> + writel(csi2rx->vc_select[i],
> csi2rx->base + CSI2RX_STREAM_DATA_CFG_REG(i));
>
> writel(CSI2RX_STREAM_CTRL_START,
> @@ -486,18 +496,59 @@ static int csi2rx_log_status(struct v4l2_subdev *sd)
> return 0;
> }
>
> +static void csi2rx_update_vc_select(struct csi2rx_priv *csi2rx,
> + struct v4l2_subdev_state *state)
> +{
> + struct v4l2_mbus_frame_desc fd = {0};
> + struct v4l2_subdev_route *route;
> + unsigned int i;
> + int ret;
> +
> + /* Capture VC=0 by default */
> + for (i = 0; i < CSI2RX_STREAMS_MAX; i++)
> + csi2rx->vc_select[i] = CSI2RX_STREAM_DATA_CFG_VC_SELECT(0);
This should be inside the if-block below, as in the other code path you
just memset the whole vc_select.
With that fixed:
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Tomi
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