Re: [PATCH v9 13/13] media: ti: Add CSI2RX support for J721E

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Jai,

Thank you for the patch.

On Fri, Aug 11, 2023 at 04:17:35PM +0530, Jai Luthra wrote:
> From: Pratyush Yadav <p.yadav@ti.com>
> 
> TI's J721E uses the Cadence CSI2RX and DPHY peripherals to facilitate
> capture over a CSI-2 bus.
> 
> The Cadence CSI2RX IP acts as a bridge between the TI specific parts and
> the CSI-2 protocol parts. TI then has a wrapper on top of this bridge
> called the SHIM layer. It takes in data from stream 0, repacks it, and
> sends it to memory over PSI-L DMA.
> 
> This driver acts as the "front end" to V4L2 client applications. It
> implements the required ioctls and buffer operations, passes the
> necessary calls on to the bridge, programs the SHIM layer, and performs
> DMA via the dmaengine API to finally return the data to a buffer
> supplied by the application.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> Co-authored-by: Vaishnav Achath <vaishnav.a@ti.com>
> Signed-off-by: Vaishnav Achath <vaishnav.a@ti.com>
> Tested-by: Vaishnav Achath <vaishnav.a@ti.com>
> Co-authored-by: Jai Luthra <j-luthra@ti.com>
> Signed-off-by: Jai Luthra <j-luthra@ti.com>
> ---
> Changes since v8:
>     - Allocate drain buffer at start of stream instead of doing it in the
>       middle, and document why it is needed in comments
>     - Call subdev's get_fmt directly for link_validation()
>     - Cleanup height/width clamping and rounding code, document it in comments
>     - Return and check errors from setup_shim()
>     - s/subdev/source for cadence csi2rx's v4l2_subdev
>     - s/ti_csi2rx_init_subdev/ti_csi2rx_notifier_register
>     - Change copyright year/author list
> 
>  MAINTAINERS                                        |    7 +
>  drivers/media/platform/ti/Kconfig                  |   12 +
>  drivers/media/platform/ti/Makefile                 |    1 +
>  drivers/media/platform/ti/j721e-csi2rx/Makefile    |    2 +
>  .../media/platform/ti/j721e-csi2rx/j721e-csi2rx.c  | 1150 ++++++++++++++++++++
>  5 files changed, 1172 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 02a3192195af..959147d6d936 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21455,6 +21455,13 @@ F:	Documentation/devicetree/bindings/media/i2c/ti,ds90*
>  F:	drivers/media/i2c/ds90*
>  F:	include/media/i2c/ds90*
>  
> +TI J721E CSI2RX DRIVER
> +M:	Jai Luthra <j-luthra@ti.com>
> +L:	linux-media@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/media/ti,j721e-csi2rx.yaml
> +F:	drivers/media/platform/ti/j721e-csi2rx/
> +
>  TI KEYSTONE MULTICORE NAVIGATOR DRIVERS
>  M:	Nishanth Menon <nm@ti.com>
>  M:	Santosh Shilimkar <ssantosh@kernel.org>
> diff --git a/drivers/media/platform/ti/Kconfig b/drivers/media/platform/ti/Kconfig
> index e1ab56c3be1f..42c908f6e1ae 100644
> --- a/drivers/media/platform/ti/Kconfig
> +++ b/drivers/media/platform/ti/Kconfig
> @@ -63,6 +63,18 @@ config VIDEO_TI_VPE_DEBUG
>  	help
>  	  Enable debug messages on VPE driver.
>  
> +config VIDEO_TI_J721E_CSI2RX
> +	tristate "TI J721E CSI2RX wrapper layer driver"
> +	depends on VIDEO_DEV && VIDEO_V4L2_SUBDEV_API
> +	depends on MEDIA_SUPPORT && MEDIA_CONTROLLER
> +	depends on PHY_CADENCE_DPHY_RX && VIDEO_CADENCE_CSI2RX

Is there a compile-time dependency on these, or just runtime ? If it's
just at runtime, it would be nice to either drop the dependency here, or
add a (...) || COMPILE_TEST

> +	depends on ARCH_K3 || COMPILE_TEST
> +	select VIDEOBUF2_DMA_CONTIG
> +	select V4L2_FWNODE
> +	help
> +	  Support for TI CSI2RX wrapper layer. This just enables the wrapper driver.
> +	  The Cadence CSI2RX bridge driver needs to be enabled separately.
> +
>  source "drivers/media/platform/ti/am437x/Kconfig"
>  source "drivers/media/platform/ti/davinci/Kconfig"
>  source "drivers/media/platform/ti/omap/Kconfig"
> diff --git a/drivers/media/platform/ti/Makefile b/drivers/media/platform/ti/Makefile
> index 98c5fe5c40d6..8a2f74c9380e 100644
> --- a/drivers/media/platform/ti/Makefile
> +++ b/drivers/media/platform/ti/Makefile
> @@ -3,5 +3,6 @@ obj-y += am437x/
>  obj-y += cal/
>  obj-y += vpe/
>  obj-y += davinci/
> +obj-y += j721e-csi2rx/
>  obj-y += omap/
>  obj-y += omap3isp/
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/Makefile b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> new file mode 100644
> index 000000000000..377afc1d6280
> --- /dev/null
> +++ b/drivers/media/platform/ti/j721e-csi2rx/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_VIDEO_TI_J721E_CSI2RX) += j721e-csi2rx.o
> diff --git a/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> new file mode 100644
> index 000000000000..301d947f6098
> --- /dev/null
> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> @@ -0,0 +1,1150 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * TI CSI2RX Shim Wrapper Driver
> + *
> + * Copyright (C) 2023 Texas Instruments Incorporated - https://www.ti.com/
> + *
> + * Author: Pratyush Yadav <p.yadav@ti.com>
> + * Author: Jai Luthra <j-luthra@ti.com>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/dmaengine.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +
> +#include <media/mipi-csi2.h>
> +#include <media/v4l2-device.h>
> +#include <media/v4l2-ioctl.h>
> +#include <media/v4l2-mc.h>
> +#include <media/videobuf2-dma-contig.h>
> +
> +#define TI_CSI2RX_MODULE_NAME		"j721e-csi2rx"
> +
> +#define SHIM_CNTL			0x10
> +#define SHIM_CNTL_PIX_RST		BIT(0)
> +
> +#define SHIM_DMACNTX			0x20
> +#define SHIM_DMACNTX_EN			BIT(31)
> +#define SHIM_DMACNTX_YUV422		GENMASK(27, 26)
> +#define SHIM_DMACNTX_SIZE		GENMASK(21, 20)
> +#define SHIM_DMACNTX_FMT		GENMASK(5, 0)
> +#define SHIM_DMACNTX_UYVY		0
> +#define SHIM_DMACNTX_VYUY		1
> +#define SHIM_DMACNTX_YUYV		2
> +#define SHIM_DMACNTX_YVYU		3
> +#define SHIM_DMACNTX_SIZE_8		0
> +#define SHIM_DMACNTX_SIZE_16		1
> +#define SHIM_DMACNTX_SIZE_32		2
> +
> +#define SHIM_PSI_CFG0			0x24
> +#define SHIM_PSI_CFG0_SRC_TAG		GENMASK(15, 0)
> +#define SHIM_PSI_CFG0_DST_TAG		GENMASK(31, 16)
> +
> +#define PSIL_WORD_SIZE_BYTES		16
> +/*
> + * There are no hard limits on the width or height. The DMA engine can handle
> + * all sizes. The max width and height are arbitrary numbers for this driver.
> + * Use 16K * 16K as the arbitrary limit. It is large enough that it is unlikely
> + * the limit will be hit in practice.
> + */
> +#define MAX_WIDTH_BYTES			SZ_16K
> +#define MAX_HEIGHT_LINES		SZ_16K
> +
> +#define DRAIN_TIMEOUT_MS		50
> +
> +struct ti_csi2rx_fmt {
> +	u32				fourcc;	/* Four character code. */
> +	u32				code;	/* Mbus code. */
> +	u32				csi_dt;	/* CSI Data type. */
> +	u8				bpp;	/* Bits per pixel. */
> +	u8				size;	/* Data size shift when unpacking. */
> +};
> +
> +struct ti_csi2rx_buffer {
> +	/* Common v4l2 buffer. Must be first. */
> +	struct vb2_v4l2_buffer		vb;
> +	struct list_head		list;
> +	struct ti_csi2rx_dev		*csi;
> +};
> +
> +enum ti_csi2rx_dma_state {
> +	TI_CSI2RX_DMA_STOPPED,	/* Streaming not started yet. */
> +	TI_CSI2RX_DMA_IDLE,	/* Streaming but no pending DMA operation. */
> +	TI_CSI2RX_DMA_ACTIVE,	/* Streaming and pending DMA operation. */
> +};
> +
> +struct ti_csi2rx_dma {
> +	/* Protects all fields in this struct. */
> +	spinlock_t			lock;
> +	struct dma_chan			*chan;
> +	/* Buffers queued to the driver, waiting to be processed by DMA. */
> +	struct list_head		queue;
> +	enum ti_csi2rx_dma_state	state;
> +	/*
> +	 * Queue of buffers submitted to DMA engine.
> +	 */
> +	struct list_head		submitted;
> +	/* Buffer to drain stale data from PSI-L endpoint */
> +	struct {
> +		void			*vaddr;
> +		dma_addr_t		paddr;
> +		size_t			len;
> +	} drain;
> +};
> +
> +struct ti_csi2rx_dev {
> +	struct device			*dev;
> +	void __iomem			*shim;
> +	struct v4l2_device		v4l2_dev;
> +	struct video_device		vdev;
> +	struct media_device		mdev;
> +	struct media_pipeline		pipe;
> +	struct media_pad		pad;
> +	struct v4l2_async_notifier	notifier;
> +	struct v4l2_subdev		*source;
> +	struct vb2_queue		vidq;
> +	struct mutex			mutex; /* To serialize ioctls. */
> +	struct v4l2_format		v_fmt;
> +	struct ti_csi2rx_dma		dma;
> +	u32				sequence;
> +};
> +
> +static const struct ti_csi2rx_fmt formats[] = {

It would be nice to prefix local symbols to avoid namespace clashes,
even if they're static. ti_csi2rx_formats could be a good name. Same
below where applicable, and possibly above for some macro names.

> +	{
> +		.fourcc			= V4L2_PIX_FMT_YUYV,
> +		.code			= MEDIA_BUS_FMT_YUYV8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_UYVY,
> +		.code			= MEDIA_BUS_FMT_UYVY8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_YVYU,
> +		.code			= MEDIA_BUS_FMT_YVYU8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_VYUY,
> +		.code			= MEDIA_BUS_FMT_VYUY8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SBGGR8,
> +		.code			= MEDIA_BUS_FMT_SBGGR8_1X8,
> +		.csi_dt			= MIPI_CSI2_DT_RAW8,
> +		.bpp			= 8,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SGBRG8,
> +		.code			= MEDIA_BUS_FMT_SGBRG8_1X8,
> +		.csi_dt			= MIPI_CSI2_DT_RAW8,
> +		.bpp			= 8,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SGRBG8,
> +		.code			= MEDIA_BUS_FMT_SGRBG8_1X8,
> +		.csi_dt			= MIPI_CSI2_DT_RAW8,
> +		.bpp			= 8,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SRGGB8,
> +		.code			= MEDIA_BUS_FMT_SRGGB8_1X8,
> +		.csi_dt			= MIPI_CSI2_DT_RAW8,
> +		.bpp			= 8,
> +		.size			= SHIM_DMACNTX_SIZE_8,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SBGGR10,
> +		.code			= MEDIA_BUS_FMT_SBGGR10_1X10,
> +		.csi_dt			= MIPI_CSI2_DT_RAW10,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SGBRG10,
> +		.code			= MEDIA_BUS_FMT_SGBRG10_1X10,
> +		.csi_dt			= MIPI_CSI2_DT_RAW10,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SGRBG10,
> +		.code			= MEDIA_BUS_FMT_SGRBG10_1X10,
> +		.csi_dt			= MIPI_CSI2_DT_RAW10,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_SRGGB10,
> +		.code			= MEDIA_BUS_FMT_SRGGB10_1X10,
> +		.csi_dt			= MIPI_CSI2_DT_RAW10,
> +		.bpp			= 16,
> +		.size			= SHIM_DMACNTX_SIZE_16,
> +	},
> +
> +	/* More formats can be supported but they are not listed for now. */
> +};
> +
> +static const unsigned int num_formats = ARRAY_SIZE(formats);

I would use ARRAY_SIZE(formats) below and drop num_formats, as I don't
think it improves readability, but I don't insist.

> +
> +/* Forward declaration needed by ti_csi2rx_dma_callback. */
> +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> +			       struct ti_csi2rx_buffer *buf);
> +
> +static const struct ti_csi2rx_fmt *find_format_by_pix(u32 pixelformat)

Maybe "_by_fourcc" ? That's nitpicking though.

> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < num_formats; i++) {
> +		if (formats[i].fourcc == pixelformat)
> +			return &formats[i];
> +	}
> +
> +	return NULL;
> +}
> +
> +static const struct ti_csi2rx_fmt *find_format_by_code(u32 code)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < num_formats; i++) {
> +		if (formats[i].code == code)
> +			return &formats[i];
> +	}
> +
> +	return NULL;
> +}
> +
> +static void ti_csi2rx_fill_fmt(const struct ti_csi2rx_fmt *csi_fmt,
> +			       struct v4l2_format *v4l2_fmt)
> +{
> +	struct v4l2_pix_format *pix = &v4l2_fmt->fmt.pix;
> +	unsigned int pixels_in_word;
> +	u8 bpp = ALIGN(csi_fmt->bpp, 8);

All bpp values are multiple of 8, is ALIGN() needed ?

> +
> +	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> +
> +	/* Clamp width and height to sensible maximums (16K x 16K) */
> +	pix->width = clamp_t(unsigned int, pix->width,
> +			     pixels_in_word,
> +			     MAX_WIDTH_BYTES * 8 / bpp);
> +	pix->height = clamp_t(unsigned int, pix->height, 1, MAX_HEIGHT_LINES);
> +
> +	/* Width should be a multiple of transfer word-size */
> +	pix->width = rounddown(pix->width, pixels_in_word);
> +
> +	v4l2_fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	pix->pixelformat = csi_fmt->fourcc;
> +	pix->colorspace = V4L2_COLORSPACE_SRGB;

You should fill the other colorspace-related fields.

> +	pix->bytesperline = pix->width * (bpp / 8);
> +	pix->sizeimage = pix->bytesperline * pix->height;
> +}
> +
> +static int ti_csi2rx_querycap(struct file *file, void *priv,
> +			      struct v4l2_capability *cap)
> +{
> +	strscpy(cap->driver, TI_CSI2RX_MODULE_NAME, sizeof(cap->driver));
> +	strscpy(cap->card, TI_CSI2RX_MODULE_NAME, sizeof(cap->card));
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_enum_fmt_vid_cap(struct file *file, void *priv,
> +				      struct v4l2_fmtdesc *f)
> +{
> +	const struct ti_csi2rx_fmt *fmt = NULL;
> +
> +	if (f->mbus_code) {
> +		/* 1-to-1 mapping between bus formats and pixel formats */
> +		if (f->index > 0)
> +			return -EINVAL;
> +
> +		fmt = find_format_by_code(f->mbus_code);
> +	} else {
> +		if (f->index >= num_formats)
> +			return -EINVAL;
> +
> +		fmt = &formats[f->index];
> +	}
> +
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	f->pixelformat = fmt->fourcc;
> +	memset(f->reserved, 0, sizeof(f->reserved));
> +	f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_g_fmt_vid_cap(struct file *file, void *prov,
> +				   struct v4l2_format *f)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +
> +	*f = csi->v_fmt;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_try_fmt_vid_cap(struct file *file, void *priv,
> +				     struct v4l2_format *f)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +
> +	/*
> +	 * Default to the first format if the requested pixel format code isn't
> +	 * supported.
> +	 */
> +	fmt = find_format_by_pix(f->fmt.pix.pixelformat);
> +	if (!fmt)
> +		fmt = &formats[0];
> +
> +	/* Interlaced formats are not supported. */
> +	f->fmt.pix.field = V4L2_FIELD_NONE;
> +
> +	ti_csi2rx_fill_fmt(fmt, f);
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_s_fmt_vid_cap(struct file *file, void *priv,
> +				   struct v4l2_format *f)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +	struct vb2_queue *q = &csi->vidq;
> +	int ret;
> +
> +	if (vb2_is_busy(q))
> +		return -EBUSY;
> +
> +	ret = ti_csi2rx_try_fmt_vid_cap(file, priv, f);
> +	if (ret < 0)
> +		return ret;
> +
> +	csi->v_fmt = *f;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_enum_framesizes(struct file *file, void *fh,
> +				     struct v4l2_frmsizeenum *fsize)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +	unsigned int pixels_in_word;
> +	u8 bpp;
> +
> +	fmt = find_format_by_pix(fsize->pixel_format);
> +	if (!fmt || fsize->index != 0)
> +		return -EINVAL;
> +
> +	bpp = ALIGN(fmt->bpp, 8);
> +
> +	/*
> +	 * Number of pixels in one PSI-L word. The transfer happens in multiples
> +	 * of PSI-L word sizes.
> +	 */
> +	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> +
> +	fsize->type = V4L2_FRMSIZE_TYPE_STEPWISE;
> +	fsize->stepwise.min_width = pixels_in_word;
> +	fsize->stepwise.max_width = rounddown(MAX_WIDTH_BYTES * 8 / bpp,
> +					      pixels_in_word);
> +	fsize->stepwise.step_width = pixels_in_word;
> +	fsize->stepwise.min_height = 1;
> +	fsize->stepwise.max_height = MAX_HEIGHT_LINES;
> +	fsize->stepwise.step_height = 1;
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_ioctl_ops csi_ioctl_ops = {
> +	.vidioc_querycap      = ti_csi2rx_querycap,
> +	.vidioc_enum_fmt_vid_cap = ti_csi2rx_enum_fmt_vid_cap,
> +	.vidioc_try_fmt_vid_cap = ti_csi2rx_try_fmt_vid_cap,
> +	.vidioc_g_fmt_vid_cap = ti_csi2rx_g_fmt_vid_cap,
> +	.vidioc_s_fmt_vid_cap = ti_csi2rx_s_fmt_vid_cap,
> +	.vidioc_enum_framesizes = ti_csi2rx_enum_framesizes,
> +	.vidioc_reqbufs       = vb2_ioctl_reqbufs,
> +	.vidioc_create_bufs   = vb2_ioctl_create_bufs,
> +	.vidioc_prepare_buf   = vb2_ioctl_prepare_buf,
> +	.vidioc_querybuf      = vb2_ioctl_querybuf,
> +	.vidioc_qbuf          = vb2_ioctl_qbuf,
> +	.vidioc_dqbuf         = vb2_ioctl_dqbuf,
> +	.vidioc_expbuf        = vb2_ioctl_expbuf,
> +	.vidioc_streamon      = vb2_ioctl_streamon,
> +	.vidioc_streamoff     = vb2_ioctl_streamoff,
> +};
> +
> +static const struct v4l2_file_operations csi_fops = {
> +	.owner = THIS_MODULE,
> +	.open = v4l2_fh_open,
> +	.release = vb2_fop_release,
> +	.read = vb2_fop_read,
> +	.poll = vb2_fop_poll,
> +	.unlocked_ioctl = video_ioctl2,
> +	.mmap = vb2_fop_mmap,
> +};
> +
> +static int csi_async_notifier_bound(struct v4l2_async_notifier *notifier,
> +				    struct v4l2_subdev *subdev,
> +				    struct v4l2_async_connection *asc)
> +{
> +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> +
> +	csi->source = subdev;
> +
> +	return 0;
> +}
> +
> +static int csi_async_notifier_complete(struct v4l2_async_notifier *notifier)
> +{
> +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> +	struct video_device *vdev = &csi->vdev;
> +	int ret;
> +
> +	ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
> +	if (ret)
> +		return ret;
> +
> +	ret = v4l2_create_fwnode_links_to_pad(csi->source, &csi->pad,
> +					      MEDIA_LNK_FL_IMMUTABLE | MEDIA_LNK_FL_ENABLED);
> +
> +	if (ret) {
> +		video_unregister_device(vdev);
> +		return ret;
> +	}
> +
> +	return v4l2_device_register_subdev_nodes(&csi->v4l2_dev);

You should call video_unregister_device() if this fails.

I'm tempted, however, to register the video device at probe time, not in
this function.

> +}
> +
> +static const struct v4l2_async_notifier_operations csi_async_notifier_ops = {
> +	.bound = csi_async_notifier_bound,
> +	.complete = csi_async_notifier_complete,
> +};
> +
> +static int ti_csi2rx_notifier_register(struct ti_csi2rx_dev *csi)
> +{
> +	struct fwnode_handle *fwnode;
> +	struct v4l2_async_connection *asc;
> +	struct device_node *node;
> +	int ret;
> +
> +	node = of_get_child_by_name(csi->dev->of_node, "csi-bridge");
> +	if (!node)
> +		return -EINVAL;
> +
> +	fwnode = of_fwnode_handle(node);
> +	if (!fwnode) {
> +		of_node_put(node);
> +		return -EINVAL;
> +	}
> +
> +	v4l2_async_nf_init(&csi->notifier, &csi->v4l2_dev);
> +	csi->notifier.ops = &csi_async_notifier_ops;
> +
> +	asc = v4l2_async_nf_add_fwnode(&csi->notifier, fwnode,
> +				       struct v4l2_async_connection);
> +	of_node_put(node);
> +	if (IS_ERR(asc)) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return PTR_ERR(asc);
> +	}
> +
> +	ret = v4l2_async_nf_register(&csi->notifier);
> +	if (ret) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_setup_shim(struct ti_csi2rx_dev *csi)
> +{
> +	const struct ti_csi2rx_fmt *fmt;
> +	unsigned int reg;
> +
> +	fmt = find_format_by_pix(csi->v_fmt.fmt.pix.pixelformat);
> +	if (!fmt) {
> +		dev_err(csi->dev, "Pixelformat 0x%x is not supported\n",

Use %p4cc to print a fourcc. You need to pass the pixel format by
address to dev_err() then, not by value.

Can this happen though, given that the set format handler should never
allow setting a format not supported by the driver ? I think I'd drop
the error check. The function can then become a void function.

> +			csi->v_fmt.fmt.pix.pixelformat);
> +		return -EINVAL;
> +	}
> +
> +	/* De-assert the pixel interface reset. */
> +	reg = SHIM_CNTL_PIX_RST;
> +	writel(reg, csi->shim + SHIM_CNTL);
> +
> +	reg = SHIM_DMACNTX_EN;
> +	reg |= FIELD_PREP(SHIM_DMACNTX_FMT, fmt->csi_dt);
> +
> +	/*
> +	 * Using the values from the documentation gives incorrect ordering for
> +	 * the luma and chroma components. In practice, the "reverse" format
> +	 * gives the correct image. So for example, if the image is in UYVY, the
> +	 * reverse would be YVYU.
> +	 */
> +	switch (fmt->fourcc) {
> +	case V4L2_PIX_FMT_UYVY:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_YVYU);
> +		break;
> +	case V4L2_PIX_FMT_VYUY:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_YUYV);
> +		break;
> +	case V4L2_PIX_FMT_YUYV:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_VYUY);
> +		break;
> +	case V4L2_PIX_FMT_YVYU:
> +		reg |= FIELD_PREP(SHIM_DMACNTX_YUV422,
> +					SHIM_DMACNTX_UYVY);
> +		break;
> +	default:
> +		/* Ignore if not YUV 4:2:2 */
> +		break;
> +	}
> +
> +	reg |= FIELD_PREP(SHIM_DMACNTX_SIZE, fmt->size);
> +
> +	writel(reg, csi->shim + SHIM_DMACNTX);
> +
> +	reg = FIELD_PREP(SHIM_PSI_CFG0_SRC_TAG, 0) |
> +	      FIELD_PREP(SHIM_PSI_CFG0_DST_TAG, 0);
> +	writel(reg, csi->shim + SHIM_PSI_CFG0);
> +
> +	return 0;
> +}
> +
> +static void ti_csi2rx_drain_callback(void *param)
> +{
> +	struct completion *drain_complete = param;
> +
> +	complete(drain_complete);
> +}
> +
> +/** Drain the stale data left at the PSI-L endpoint.

This isn't kerneldoc, so

/*
 * Drain the stale data left at the PSI-L endpoint.

> + *
> + * This might happen if no buffers are queued in time but source is still
> + * streaming. Or rarely it may happen while stopping the stream. To prevent
> + * that stale data corrupting the subsequent transactions, it is required to
> + * issue DMA requests to drain it out.
> + */
> +static int ti_csi2rx_drain_dma(struct ti_csi2rx_dev *csi)
> +{
> +	struct dma_async_tx_descriptor *desc;
> +	struct completion drain_complete;
> +	dma_cookie_t cookie;
> +	int ret;
> +
> +	init_completion(&drain_complete);
> +
> +	desc = dmaengine_prep_slave_single(csi->dma.chan, csi->dma.drain.paddr,
> +					   csi->dma.drain.len, DMA_DEV_TO_MEM,
> +					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!desc) {
> +		ret = -EIO;
> +		goto out;
> +	}
> +
> +	desc->callback = ti_csi2rx_drain_callback;
> +	desc->callback_param = &drain_complete;
> +
> +	cookie = dmaengine_submit(desc);
> +	ret = dma_submit_error(cookie);
> +	if (ret)
> +		goto out;
> +
> +	dma_async_issue_pending(csi->dma.chan);
> +
> +	if (!wait_for_completion_timeout(&drain_complete,
> +					 msecs_to_jiffies(DRAIN_TIMEOUT_MS))) {
> +		dmaengine_terminate_sync(csi->dma.chan);
> +		ret = -ETIMEDOUT;
> +		goto out;
> +	}
> +out:
> +	return ret;
> +}
> +
> +static void ti_csi2rx_dma_callback(void *param)
> +{
> +	struct ti_csi2rx_buffer *buf = param;
> +	struct ti_csi2rx_dev *csi = buf->csi;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	unsigned long flags;
> +
> +	/*
> +	 * TODO: Derive the sequence number from the CSI2RX frame number
> +	 * hardware monitor registers.
> +	 */
> +	buf->vb.vb2_buf.timestamp = ktime_get_ns();
> +	buf->vb.sequence = csi->sequence++;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +
> +	WARN_ON(!list_is_first(&buf->list, &dma->submitted));
> +	vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> +	list_del(&buf->list);
> +
> +	/* If there are more buffers to process then start their transfer. */
> +	while (!list_empty(&dma->queue)) {
> +		buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +
> +		if (ti_csi2rx_start_dma(csi, buf)) {
> +			dev_err(csi->dev, "Failed to queue the next buffer for DMA\n");
> +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +		} else {
> +			list_move_tail(&buf->list, &dma->submitted);
> +		}
> +	}
> +
> +	if (list_empty(&dma->submitted))
> +		dma->state = TI_CSI2RX_DMA_IDLE;
> +
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static int ti_csi2rx_start_dma(struct ti_csi2rx_dev *csi,
> +			       struct ti_csi2rx_buffer *buf)
> +{
> +	unsigned long addr;
> +	struct dma_async_tx_descriptor *desc;
> +	size_t len = csi->v_fmt.fmt.pix.sizeimage;
> +	dma_cookie_t cookie;
> +	int ret = 0;
> +
> +	addr = vb2_dma_contig_plane_dma_addr(&buf->vb.vb2_buf, 0);
> +	desc = dmaengine_prep_slave_single(csi->dma.chan, addr, len,
> +					   DMA_DEV_TO_MEM,
> +					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!desc)
> +		return -EIO;
> +
> +	desc->callback = ti_csi2rx_dma_callback;
> +	desc->callback_param = buf;
> +
> +	cookie = dmaengine_submit(desc);
> +	ret = dma_submit_error(cookie);
> +	if (ret)
> +		return ret;
> +
> +	dma_async_issue_pending(csi->dma.chan);
> +
> +	return 0;
> +}
> +
> +static void ti_csi2rx_cleanup_buffers(struct ti_csi2rx_dev *csi,
> +				      enum vb2_buffer_state buf_state)
> +{
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	struct ti_csi2rx_buffer *buf, *tmp;
> +	enum ti_csi2rx_dma_state state;
> +	unsigned long flags;
> +	int ret;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	state = csi->dma.state;
> +	dma->state = TI_CSI2RX_DMA_STOPPED;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	if (state != TI_CSI2RX_DMA_STOPPED) {
> +		/*
> +		 * Normal DMA termination sometimes does not clean up pending
> +		 * data on the endpoint.
> +		 */
> +		ret = ti_csi2rx_drain_dma(csi);
> +		if (ret)
> +			dev_dbg(csi->dev,
> +				"Failed to drain DMA. Next frame might be bogus\n");

A dev_warn() may be more appropriate, this seems quite important.

> +	}

A blank line would be nice here.

> +	ret = dmaengine_terminate_sync(csi->dma.chan);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop DMA: %d\n", ret);

When called from ti_csi2rx_start_streaming() there's already a
dmaengine_terminate_sync(), and there's also a call to the same function
in ti_csi2rx_drain_dma() called above. Could we avoid calling the
function multiple times ? I think stopping the DMA engine should be
moved to a separate function, as it doesn't fit with the
ti_csi2rx_cleanup_buffers() name.

> +
> +	dma_free_coherent(csi->dev, dma->drain.len,
> +			  dma->drain.vaddr, dma->drain.paddr);
> +	dma->drain.vaddr = NULL;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	list_for_each_entry_safe(buf, tmp, &csi->dma.queue, list) {
> +		list_del(&buf->list);
> +		vb2_buffer_done(&buf->vb.vb2_buf, buf_state);
> +	}
> +	list_for_each_entry_safe(buf, tmp, &csi->dma.submitted, list) {
> +		list_del(&buf->list);
> +		vb2_buffer_done(&buf->vb.vb2_buf, buf_state);
> +	}
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +}
> +
> +static int ti_csi2rx_queue_setup(struct vb2_queue *q, unsigned int *nbuffers,
> +				 unsigned int *nplanes, unsigned int sizes[],
> +				 struct device *alloc_devs[])
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(q);
> +	unsigned int size = csi->v_fmt.fmt.pix.sizeimage;
> +
> +	if (*nplanes) {
> +		if (sizes[0] < size)
> +			return -EINVAL;
> +		size = sizes[0];
> +	}
> +
> +	*nplanes = 1;
> +	sizes[0] = size;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_buffer_prepare(struct vb2_buffer *vb)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> +	unsigned long size = csi->v_fmt.fmt.pix.sizeimage;
> +
> +	if (vb2_plane_size(vb, 0) < size) {
> +		dev_err(csi->dev, "Data will not fit into plane\n");
> +		return -EINVAL;
> +	}
> +
> +	vb2_set_plane_payload(vb, 0, size);
> +	return 0;
> +}
> +
> +static void ti_csi2rx_buffer_queue(struct vb2_buffer *vb)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vb->vb2_queue);
> +	struct ti_csi2rx_buffer *buf;
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	bool restart_dma = false;
> +	unsigned long flags = 0;
> +	int ret;
> +
> +	buf = container_of(vb, struct ti_csi2rx_buffer, vb.vb2_buf);
> +	buf->csi = csi;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	/*
> +	 * Usually the DMA callback takes care of queueing the pending buffers.
> +	 * But if DMA has stalled due to lack of buffers, restart it now.
> +	 */
> +	if (dma->state == TI_CSI2RX_DMA_IDLE) {
> +		/*
> +		 * Do not restart DMA with the lock held because
> +		 * ti_csi2rx_drain_dma() might block for completion.
> +		 * There won't be a race on queueing DMA anyway since the
> +		 * callback is not being fired.
> +		 */
> +		restart_dma = true;
> +		dma->state = TI_CSI2RX_DMA_ACTIVE;
> +	} else {
> +		list_add_tail(&buf->list, &dma->queue);
> +	}
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	if (restart_dma) {
> +		/*
> +		 * Once frames start dropping, some data gets stuck in the DMA
> +		 * pipeline somewhere. So the first DMA transfer after frame
> +		 * drops gives a partial frame. This is obviously not useful to
> +		 * the application and will only confuse it. Issue a DMA
> +		 * transaction to drain that up.
> +		 */

Another option would be to return the frame to userspace with the error
flag set. That would give an earlier indication to applications that
something went wrong. Up to you.

> +		ret = ti_csi2rx_drain_dma(csi);
> +		if (ret)
> +			dev_warn(csi->dev,
> +				 "Failed to drain DMA. Next frame might be bogus\n");
> +
> +		ret = ti_csi2rx_start_dma(csi, buf);
> +		if (ret) {
> +			dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> +			spin_lock_irqsave(&dma->lock, flags);
> +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_ERROR);
> +			dma->state = TI_CSI2RX_DMA_IDLE;
> +			spin_unlock_irqrestore(&dma->lock, flags);
> +		} else {
> +			spin_lock_irqsave(&dma->lock, flags);
> +			list_add_tail(&buf->list, &dma->submitted);
> +			spin_unlock_irqrestore(&dma->lock, flags);
> +		}
> +	}
> +}
> +
> +static int ti_csi2rx_start_streaming(struct vb2_queue *vq, unsigned int count)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	struct ti_csi2rx_buffer *buf;
> +	unsigned long flags;
> +	int ret = 0;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	if (list_empty(&dma->queue))
> +		ret = -EIO;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +	if (ret)
> +		return ret;
> +
> +	dma->drain.len = csi->v_fmt.fmt.pix.sizeimage;
> +	dma->drain.vaddr = dma_alloc_coherent(csi->dev, dma->drain.len,
> +					      &dma->drain.paddr, GFP_KERNEL);
> +	if (!dma->drain.vaddr)
> +		return -ENOMEM;
> +
> +	ret = video_device_pipeline_start(&csi->vdev, &csi->pipe);
> +	if (ret)
> +		goto err;
> +
> +	ret = ti_csi2rx_setup_shim(csi);
> +	if (ret)
> +		goto err;
> +
> +	csi->sequence = 0;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +
> +	ret = ti_csi2rx_start_dma(csi, buf);
> +	if (ret) {
> +		dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> +		spin_unlock_irqrestore(&dma->lock, flags);
> +		goto err_pipeline;
> +	}
> +
> +	list_move_tail(&buf->list, &dma->submitted);
> +	dma->state = TI_CSI2RX_DMA_ACTIVE;
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	ret = v4l2_subdev_call(csi->source, video, s_stream, 1);
> +	if (ret)
> +		goto err_dma;
> +
> +	return 0;
> +
> +err_dma:
> +	dmaengine_terminate_sync(csi->dma.chan);
> +	writel(0, csi->shim + SHIM_DMACNTX);
> +err_pipeline:
> +	video_device_pipeline_stop(&csi->vdev);
> +err:
> +	ti_csi2rx_cleanup_buffers(csi, VB2_BUF_STATE_QUEUED);
> +	return ret;
> +}
> +
> +static void ti_csi2rx_stop_streaming(struct vb2_queue *vq)
> +{
> +	struct ti_csi2rx_dev *csi = vb2_get_drv_priv(vq);
> +	int ret;
> +
> +	video_device_pipeline_stop(&csi->vdev);
> +
> +	writel(0, csi->shim + SHIM_CNTL);
> +	writel(0, csi->shim + SHIM_DMACNTX);
> +
> +	ret = v4l2_subdev_call(csi->source, video, s_stream, 0);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop subdev stream\n");
> +
> +	ti_csi2rx_cleanup_buffers(csi, VB2_BUF_STATE_ERROR);
> +}
> +
> +static const struct vb2_ops csi_vb2_qops = {
> +	.queue_setup = ti_csi2rx_queue_setup,
> +	.buf_prepare = ti_csi2rx_buffer_prepare,
> +	.buf_queue = ti_csi2rx_buffer_queue,
> +	.start_streaming = ti_csi2rx_start_streaming,
> +	.stop_streaming = ti_csi2rx_stop_streaming,
> +	.wait_prepare = vb2_ops_wait_prepare,
> +	.wait_finish = vb2_ops_wait_finish,
> +};
> +
> +static int ti_csi2rx_init_vb2q(struct ti_csi2rx_dev *csi)
> +{
> +	struct vb2_queue *q = &csi->vidq;
> +	int ret;
> +
> +	q->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	q->io_modes = VB2_MMAP | VB2_DMABUF;
> +	q->drv_priv = csi;
> +	q->buf_struct_size = sizeof(struct ti_csi2rx_buffer);
> +	q->ops = &csi_vb2_qops;
> +	q->mem_ops = &vb2_dma_contig_memops;
> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	q->dev = dmaengine_get_dma_device(csi->dma.chan);
> +	q->lock = &csi->mutex;
> +	q->min_buffers_needed = 1;
> +
> +	ret = vb2_queue_init(q);
> +	if (ret)
> +		return ret;
> +
> +	csi->vdev.queue = q;
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_link_validate(struct media_link *link)
> +{
> +	struct media_entity *entity = link->sink->entity;
> +	struct video_device *vdev = media_entity_to_video_device(entity);
> +	struct ti_csi2rx_dev *csi = container_of(vdev, struct ti_csi2rx_dev, vdev);
> +	struct v4l2_pix_format *csi_fmt = &csi->v_fmt.fmt.pix;
> +	struct v4l2_subdev_format source_fmt = {
> +		.which	= V4L2_SUBDEV_FORMAT_ACTIVE,
> +		.pad	= link->source->index,
> +	};
> +	const struct ti_csi2rx_fmt *ti_fmt;
> +	int ret;
> +
> +	ret = v4l2_subdev_call_state_active(csi->source, pad,
> +					    get_fmt, &source_fmt);
> +	if (ret)
> +		return ret;
> +
> +	if (source_fmt.format.width != csi_fmt->width) {
> +		dev_dbg(csi->dev, "Width does not match (source %u, sink %u)\n",
> +			source_fmt.format.width, csi_fmt->width);
> +		return -EPIPE;
> +	}
> +
> +	if (source_fmt.format.height != csi_fmt->height) {
> +		dev_dbg(csi->dev, "Height does not match (source %u, sink %u)\n",
> +			source_fmt.format.height, csi_fmt->height);
> +		return -EPIPE;
> +	}
> +
> +	if (source_fmt.format.field != csi_fmt->field &&
> +	    csi_fmt->field != V4L2_FIELD_NONE) {
> +		dev_dbg(csi->dev, "Field does not match (source %u, sink %u)\n",
> +			source_fmt.format.field, csi_fmt->field);
> +		return -EPIPE;
> +	}
> +
> +	ti_fmt = find_format_by_code(source_fmt.format.code);
> +	if (!ti_fmt) {
> +		dev_dbg(csi->dev, "Media bus format 0x%x not supported\n",
> +			source_fmt.format.code);
> +		return -EPIPE;
> +	}
> +
> +	if (ti_fmt->fourcc != csi_fmt->pixelformat) {
> +		dev_dbg(csi->dev,
> +			"Cannot transform source fmt 0x%x to sink fmt 0x%x\n",
> +			ti_fmt->fourcc, csi_fmt->pixelformat);
> +		return -EPIPE;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct media_entity_operations ti_csi2rx_video_entity_ops = {
> +	.link_validate = ti_csi2rx_link_validate,
> +};
> +
> +static int ti_csi2rx_init_dma(struct ti_csi2rx_dev *csi)
> +{
> +	struct dma_slave_config cfg = {
> +		.src_addr_width = DMA_SLAVE_BUSWIDTH_16_BYTES,
> +	};
> +	int ret;
> +
> +	INIT_LIST_HEAD(&csi->dma.queue);
> +	INIT_LIST_HEAD(&csi->dma.submitted);
> +	spin_lock_init(&csi->dma.lock);
> +
> +	csi->dma.state = TI_CSI2RX_DMA_STOPPED;
> +
> +	csi->dma.chan = dma_request_chan(csi->dev, "rx0");
> +	if (IS_ERR(csi->dma.chan))
> +		return PTR_ERR(csi->dma.chan);
> +
> +	ret = dmaengine_slave_config(csi->dma.chan, &cfg);
> +	if (ret) {
> +		dma_release_channel(csi->dma.chan);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_v4l2_init(struct ti_csi2rx_dev *csi)
> +{
> +	struct media_device *mdev = &csi->mdev;
> +	struct video_device *vdev = &csi->vdev;
> +	const struct ti_csi2rx_fmt *fmt;
> +	struct v4l2_pix_format *pix_fmt = &csi->v_fmt.fmt.pix;
> +	int ret;
> +
> +	fmt = find_format_by_pix(V4L2_PIX_FMT_UYVY);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	pix_fmt->width = 640;
> +	pix_fmt->height = 480;
> +	pix_fmt->field = V4L2_FIELD_NONE;
> +
> +	ti_csi2rx_fill_fmt(fmt, &csi->v_fmt);
> +
> +	mdev->dev = csi->dev;
> +	mdev->hw_revision = 1;
> +	strscpy(mdev->model, "TI-CSI2RX", sizeof(mdev->model));
> +
> +	media_device_init(mdev);
> +
> +	strscpy(vdev->name, TI_CSI2RX_MODULE_NAME, sizeof(vdev->name));
> +	vdev->v4l2_dev = &csi->v4l2_dev;
> +	vdev->vfl_dir = VFL_DIR_RX;
> +	vdev->fops = &csi_fops;
> +	vdev->ioctl_ops = &csi_ioctl_ops;
> +	vdev->release = video_device_release_empty;
> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING |
> +			    V4L2_CAP_IO_MC;
> +	vdev->lock = &csi->mutex;
> +	video_set_drvdata(vdev, csi);
> +
> +	csi->pad.flags = MEDIA_PAD_FL_SINK;
> +	vdev->entity.ops = &ti_csi2rx_video_entity_ops;
> +	ret = media_entity_pads_init(&csi->vdev.entity, 1, &csi->pad);
> +	if (ret)
> +		return ret;
> +
> +	csi->v4l2_dev.mdev = mdev;
> +
> +	ret = v4l2_device_register(csi->dev, &csi->v4l2_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = media_device_register(mdev);
> +	if (ret) {
> +		v4l2_device_unregister(&csi->v4l2_dev);
> +		media_device_cleanup(mdev);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void ti_csi2rx_cleanup_dma(struct ti_csi2rx_dev *csi)
> +{
> +	dma_release_channel(csi->dma.chan);
> +}
> +
> +static void ti_csi2rx_cleanup_v4l2(struct ti_csi2rx_dev *csi)
> +{
> +	media_device_unregister(&csi->mdev);
> +	v4l2_device_unregister(&csi->v4l2_dev);
> +	media_device_cleanup(&csi->mdev);
> +}
> +
> +static void ti_csi2rx_cleanup_subdev(struct ti_csi2rx_dev *csi)
> +{
> +	v4l2_async_nf_unregister(&csi->notifier);
> +	v4l2_async_nf_cleanup(&csi->notifier);
> +}
> +
> +static void ti_csi2rx_cleanup_vb2q(struct ti_csi2rx_dev *csi)
> +{
> +	vb2_queue_release(&csi->vidq);
> +}
> +
> +static int ti_csi2rx_probe(struct platform_device *pdev)
> +{
> +	struct ti_csi2rx_dev *csi;
> +	struct resource *res;
> +	int ret;
> +
> +	csi = devm_kzalloc(&pdev->dev, sizeof(*csi), GFP_KERNEL);
> +	if (!csi)
> +		return -ENOMEM;
> +
> +	csi->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, csi);
> +
> +	mutex_init(&csi->mutex);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	csi->shim = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(csi->shim)) {
> +		ret = PTR_ERR(csi->shim);
> +		goto err_mutex;
> +	}
> +
> +	ret = ti_csi2rx_init_dma(csi);
> +	if (ret)
> +		goto err_mutex;
> +
> +	ret = ti_csi2rx_v4l2_init(csi);
> +	if (ret)
> +		goto err_dma;
> +
> +	ret = ti_csi2rx_init_vb2q(csi);
> +	if (ret)
> +		goto err_v4l2;
> +
> +	ret = ti_csi2rx_notifier_register(csi);
> +	if (ret)
> +		goto err_vb2q;
> +
> +	ret = of_platform_populate(csi->dev->of_node, NULL, NULL, csi->dev);
> +	if (ret) {
> +		dev_err(csi->dev, "Failed to create children: %d\n", ret);
> +		goto err_subdev;
> +	}
> +
> +	return 0;
> +
> +err_subdev:
> +	ti_csi2rx_cleanup_subdev(csi);
> +err_vb2q:
> +	ti_csi2rx_cleanup_vb2q(csi);
> +err_v4l2:
> +	ti_csi2rx_cleanup_v4l2(csi);
> +err_dma:
> +	ti_csi2rx_cleanup_dma(csi);
> +err_mutex:
> +	mutex_destroy(&csi->mutex);
> +	return ret;
> +}
> +
> +static int ti_csi2rx_remove(struct platform_device *pdev)
> +{
> +	struct ti_csi2rx_dev *csi = platform_get_drvdata(pdev);
> +
> +	video_unregister_device(&csi->vdev);
> +
> +	ti_csi2rx_cleanup_vb2q(csi);
> +	ti_csi2rx_cleanup_subdev(csi);
> +	ti_csi2rx_cleanup_v4l2(csi);
> +	ti_csi2rx_cleanup_dma(csi);
> +
> +	mutex_destroy(&csi->mutex);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ti_csi2rx_of_match[] = {
> +	{ .compatible = "ti,j721e-csi2rx-shim", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, ti_csi2rx_of_match);
> +
> +static struct platform_driver ti_csi2rx_pdrv = {
> +	.probe = ti_csi2rx_probe,
> +	.remove = ti_csi2rx_remove,
> +	.driver = {
> +		.name = TI_CSI2RX_MODULE_NAME,
> +		.of_match_table = ti_csi2rx_of_match,
> +	},
> +};
> +
> +module_platform_driver(ti_csi2rx_pdrv);
> +
> +MODULE_DESCRIPTION("TI J721E CSI2 RX Driver");
> +MODULE_AUTHOR("Pratyush Yadav <p.yadav@ti.com>");
> +MODULE_LICENSE("GPL");

-- 
Regards,

Laurent Pinchart

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