[PATCH v2] media: nxp: imx8-isi: Add virtual channel support

[Guoniu Zhou <guoniu.zhou@oss.nxp.com>]

From: Guoniu Zhou <guoniu.zhou@nxp.com>

Add virtual channel support for ISI driver.

The ISI supports different numbers of virtual channels depending on the
platform. i.MX95 supports 8 virtual channels, and i.MX8QXP/QM support 4
virtual channels. They are used in multiple camera use cases, such as
surround view. Other platforms (such as i.MX8MN/8MP/8ULP/93/91) don't
support virtual channels, and the VC_ID bits are marked as read-only.

Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Guoniu Zhou <guoniu.zhou@nxp.com>
---
Changes in v2:
- Add Rb tag from Frank Li
- Fix typo in comment(s/support/supports/)
- Update commit log to include more details about ISI virtual channel support
  on different platform
- Include bitfield.h file to fix following build error
  drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h:23:65: error: implicit declaration of function ‘FIELD_PREP’ [-Wimplicit-function-declaration]
- Link to v1: https://lore.kernel.org/r/20260309-isi_vc-v1-1-fd0b8035d1cd@nxp.com

Changes in v1:
- Depends on https://lore.kernel.org/linux-media/20251105-isi_imx95-v3-2-3987533cca1c@nxp.com/
---
 .../media/platform/nxp/imx8-isi/imx8-isi-core.h    |  3 ++
 drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c  |  4 +-
 .../media/platform/nxp/imx8-isi/imx8-isi-pipe.c    | 43 ++++++++++++++++++++++
 .../media/platform/nxp/imx8-isi/imx8-isi-regs.h    |  6 +--
 4 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.h b/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.h
index 3cbd35305af0f8026c4f76b5eb5d0864f8e36dc3..11a5e395792f11752c44d73818c825f2f175aa1d 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.h
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-core.h
@@ -256,6 +256,9 @@ struct mxc_isi_pipe {
 	u8				acquired_res;
 	u8				chained_res;
 	bool				chained;
+
+	/* Virtual channel ID for the ISI channel */
+	u8				vc;
 };
 
 struct mxc_isi_m2m {
diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
index 0187d4ab97e8e28fca9013f6864a094e08f2c570..2babb8573227de9e1aa36d9a39be41b286cf0c57 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-hw.c
@@ -338,7 +338,9 @@ static void mxc_isi_channel_set_control(struct mxc_isi_pipe *pipe,
 	} else {
 		val |= CHNL_CTRL_SRC_TYPE(CHNL_CTRL_SRC_TYPE_DEVICE);
 		val |= CHNL_CTRL_SRC_INPUT(input);
-		val |= CHNL_CTRL_MIPI_VC_ID(0); /* FIXME: For CSI-2 only */
+		val |= CHNL_CTRL_MIPI_VC_ID(pipe->vc);
+		/* Platform like i.MX95, ISI supports 8 virtual channels */
+		val |= CHNL_CTRL_VC_ID_1(pipe->vc >> 2);
 	}
 
 	mxc_isi_write(pipe, CHNL_CTRL, val);
diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-pipe.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-pipe.c
index a41c51dd9ce0f2eeb779e9aa2461593b0d635f41..cc4348ea6006ee19243aae3abceb235d00beea4d 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-pipe.c
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-pipe.c
@@ -232,6 +232,45 @@ static inline struct mxc_isi_pipe *to_isi_pipe(struct v4l2_subdev *sd)
 	return container_of(sd, struct mxc_isi_pipe, sd);
 }
 
+static int mxc_isi_get_vc(struct mxc_isi_pipe *pipe)
+{
+	struct mxc_isi_crossbar *xbar = &pipe->isi->crossbar;
+	struct device *dev = pipe->isi->dev;
+	struct v4l2_mbus_frame_desc source_fd;
+	struct v4l2_mbus_frame_desc_entry *entry = NULL;
+	unsigned int i;
+	int ret;
+
+	ret = v4l2_subdev_call(&xbar->sd, pad, get_frame_desc,
+			       xbar->num_sinks + pipe->id, &source_fd);
+	if (ret < 0) {
+		dev_err(dev, "Failed to get source frame desc from pad %u\n",
+			xbar->num_sinks + pipe->id);
+		return ret;
+	}
+
+	for (i = 0; i < source_fd.num_entries; i++) {
+		if (source_fd.entry[i].stream == 0) {
+			entry = &source_fd.entry[i];
+			break;
+		}
+	}
+
+	if (!entry) {
+		dev_err(dev, "Failed to find stream from source frame desc\n");
+		return -EPIPE;
+	}
+
+	if (entry->bus.csi2.vc >= pipe->isi->pdata->num_channels) {
+		dev_err(dev, "Virtual channel(%d) out of range\n",
+			entry->bus.csi2.vc);
+		return -EINVAL;
+	}
+
+	pipe->vc = entry->bus.csi2.vc;
+	return 0;
+}
+
 int mxc_isi_pipe_enable(struct mxc_isi_pipe *pipe)
 {
 	struct mxc_isi_crossbar *xbar = &pipe->isi->crossbar;
@@ -280,6 +319,10 @@ int mxc_isi_pipe_enable(struct mxc_isi_pipe *pipe)
 
 	v4l2_subdev_unlock_state(state);
 
+	ret = mxc_isi_get_vc(pipe);
+	if (ret)
+		return ret;
+
 	/* Configure the ISI channel. */
 	mxc_isi_channel_config(pipe, input, &in_size, &scale, &crop,
 			       sink_info->encoding, src_info->encoding);
diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h b/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h
index 1b65eccdf0da4bbc3a77c91e06fccc35d6c7e022..a4036da72f0057265e991087f21bc079bd6c6573 100644
--- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h
+++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-regs.h
@@ -6,6 +6,7 @@
 #ifndef __IMX8_ISI_REGS_H__
 #define __IMX8_ISI_REGS_H__
 
+#include <linux/bitfield.h>
 #include <linux/bits.h>
 
 /* ISI Registers Define  */
@@ -19,9 +20,8 @@
 #define CHNL_CTRL_CHAIN_BUF_NO_CHAIN				0
 #define CHNL_CTRL_CHAIN_BUF_2_CHAIN				1
 #define CHNL_CTRL_SW_RST					BIT(24)
-#define CHNL_CTRL_BLANK_PXL(n)					((n) << 16)
-#define CHNL_CTRL_BLANK_PXL_MASK				GENMASK(23, 16)
-#define CHNL_CTRL_MIPI_VC_ID(n)					((n) << 6)
+#define CHNL_CTRL_VC_ID_1(n)					FIELD_PREP(BIT(16), (n))
+#define CHNL_CTRL_MIPI_VC_ID(n)					FIELD_PREP(GENMASK(7, 6), (n))
 #define CHNL_CTRL_MIPI_VC_ID_MASK				GENMASK(7, 6)
 #define CHNL_CTRL_SRC_TYPE(n)					((n) << 4)
 #define CHNL_CTRL_SRC_TYPE_MASK					BIT(4)

---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260309-isi_vc-285fd815140e
prerequisite-patch-id: 6f139a1d54fa3e0632db9b8a736ae27037c5f45a

Best regards,
-- 
Guoniu Zhou <guoniu.zhou@nxp.com>