linux-kernel - [PATCH v8 11/18] media: ti: j721e-csi2rx: add support for processing virtual channels

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Message-ID: <20251112115459.2479225-12-r-donadkar@ti.com>
Date: Wed, 12 Nov 2025 17:24:52 +0530
From: Rishikesh Donadkar <r-donadkar@...com>
To: <jai.luthra@...ux.dev>, <laurent.pinchart@...asonboard.com>,
	<mripard@...nel.org>
CC: <r-donadkar@...com>, <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>,
	<tomi.valkeinen@...asonboard.com>, <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: [PATCH v8 11/18] media: ti: j721e-csi2rx: add support for processing virtual channels

From: Jai Luthra <j-luthra@...com>

Use get_frame_desc() to get the frame desc from the connected source,
and use the provided virtual channel instead of hardcoded one.

get_frame_desc() returns the same information when called on each stream
start, so instead get the VCs for all the routed stream at first
stream start and cache this information in the driver.

get_frame_desc() works per stream, but 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@...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>
Signed-off-by: Rishikesh Donadkar <r-donadkar@...com>
---
 .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 38 +++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
index 5c4524bf42e6e..126a62fa2c4c4 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 +111,8 @@ struct ti_csi2rx_ctx {
 	struct media_pad		pad;
 	u32				sequence;
 	u32				idx;
+	u32				vc;
+	u32				stream;
 };
 
 struct ti_csi2rx_dev {
@@ -610,6 +613,7 @@ static void ti_csi2rx_setup_shim(struct ti_csi2rx_ctx *ctx)
 	}
 
 	reg |= FIELD_PREP(SHIM_DMACNTX_SIZE, fmt->size);
+	reg |= FIELD_PREP(SHIM_DMACNTX_VC, ctx->vc);
 
 	writel(reg, csi->shim + SHIM_DMACNTX(ctx->idx));
 
@@ -884,6 +888,32 @@ static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
 	}
 }
 
+static int ti_csi2rx_get_vc(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)
+		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)
+			return fd.entry[i].bus.csi2.vc;
+	}
+
+	return -ENODEV;
+}
+
 static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
 {
 	struct ti_csi2rx_ctx *ctx = vb2_get_drv_priv(vq);
@@ -904,6 +934,14 @@ 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)
+		goto err;
+	else
+		ctx->vc = ret;
+
 	ti_csi2rx_setup_shim(ctx);
 
 	ctx->sequence = 0;
-- 
2.34.1