Re: [PATCH v12 10/17] media: ti: j721e-csi2rx: add support for processing virtual channels

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Rishikesh,

On Fri, Mar 13, 2026 at 02:36:54PM +0530, Rishikesh Donadkar wrote:
> From: Jai Luthra <j-luthra@ti.com>
> 
> Use get_frame_desc() to get the frame desc from the connected source,
> and use the provided virtual channel and DT instead of defaults.
> 
> As we don't support multiple streams yet, we will just always use
> stream 0. If the source doesn't support get_frame_desc(), fall back
> to the previous method of always capturing virtual channel 0.
> 
> 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>
> Signed-off-by: Rishikesh Donadkar <r-donadkar@ti.com>
> Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> ---
>  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 51 ++++++++++++++++++-
>  1 file changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> index 26a8eaa98b3da..24b687b4ea32a 100644
> --- a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> @@ -32,6 +32,7 @@
>  #define SHIM_DMACNTX_YUV422		GENMASK(27, 26)
>  #define SHIM_DMACNTX_DUAL_PCK_CFG	BIT(24)
>  #define SHIM_DMACNTX_SIZE		GENMASK(21, 20)
> +#define SHIM_DMACNTX_VC			GENMASK(9, 6)
>  #define SHIM_DMACNTX_FMT		GENMASK(5, 0)
>  #define SHIM_DMACNTX_YUV422_MODE_11	3
>  #define SHIM_DMACNTX_SIZE_8		0
> @@ -110,6 +111,9 @@ struct ti_csi2rx_ctx {
>  	struct media_pad		pad;
>  	u32				sequence;
>  	u32				idx;
> +	u32				vc;
> +	u32				dt;
> +	u32				stream;
>  };
>  
>  struct ti_csi2rx_dev {
> @@ -569,7 +573,7 @@ static void ti_csi2rx_setup_shim(struct ti_csi2rx_ctx *ctx)
>  	ti_csi2rx_request_max_ppc(csi);
>  
>  	reg = SHIM_DMACNTX_EN;
> -	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, fmt->csi_dt);
> +	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, ctx->dt);
>  
>  	/*
>  	 * The hardware assumes incoming YUV422 8-bit data on MIPI CSI2 bus
> @@ -608,6 +612,8 @@ static void ti_csi2rx_setup_shim(struct ti_csi2rx_ctx *ctx)
>  		break;
>  	}
>  
> +	reg |= FIELD_PREP(SHIM_DMACNTX_VC, ctx->vc);
> +
>  	writel(reg, csi->shim + SHIM_DMACNTX(ctx->idx));
>  
>  	reg = FIELD_PREP(SHIM_PSI_CFG0_SRC_TAG, 0) |
> @@ -881,12 +887,46 @@ static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
>  	}
>  }
>  
> +static int ti_csi2rx_get_vc_and_dt(struct ti_csi2rx_ctx *ctx)
> +{
> +	struct ti_csi2rx_dev *csi = ctx->csi;
> +	struct v4l2_mbus_frame_desc fd;
> +	struct media_pad *pad;
> +	int ret, i;
> +
> +	pad = media_entity_remote_pad_unique(&csi->subdev.entity, MEDIA_PAD_FL_SOURCE);
> +	if (!pad)

Same for media_entity_remote_pad_unique() it returns an error code on
error.

> +		return -ENODEV;
> +
> +	ret = v4l2_subdev_call(csi->source, pad, get_frame_desc, 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) {
> +			ctx->vc = fd.entry[i].bus.csi2.vc;
> +			ctx->dt = fd.entry[i].bus.csi2.dt;
> +			break;
> +		}
> +
> +		/* Return error if no matching stream found */
> +		if (i == fd.num_entries)
> +			return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>  {
>  	struct ti_csi2rx_ctx *ctx = vb2_get_drv_priv(vq);
>  	struct ti_csi2rx_dev *csi = ctx->csi;
>  	struct ti_csi2rx_dma *dma = &ctx->dma;
>  	struct ti_csi2rx_buffer *buf;
> +	const struct ti_csi2rx_fmt *fmt;
>  	unsigned long flags;
>  	int ret = 0;
>  
> @@ -901,6 +941,15 @@ static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
>  	if (ret)
>  		goto err;
>  
> +	ret = ti_csi2rx_get_vc_and_dt(ctx);
> +	if (ret == -ENOIOCTLCMD) {
> +		ctx->vc = 0;
> +		fmt = find_format_by_fourcc(ctx->v_fmt.fmt.pix.pixelformat);
> +		ctx->dt = fmt->csi_dt;
> +	} else if (ret < 0) {
> +		goto err;
> +	}
> +
>  	ti_csi2rx_setup_shim(ctx);
>  
>  	ctx->sequence = 0;

-- 
Regards,

Sakari Ailus