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Date:   Fri, 24 Mar 2023 20:14:25 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Vaishnav Achath <vaishnav.a@ti.com>
Cc:     linux-media@vger.kernel.org, devicetree@vger.kernel.org,
        mripard@kernel.org, mchehab@kernel.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, sakari.ailus@linux.intel.com,
        tomi.valkeinen@ideasonboard.com, linux-kernel@vger.kernel.org,
        bparrot@ti.com, niklas.soderlund+renesas@ragnatech.se,
        j-luthra@ti.com, devarsht@ti.com, praneeth@ti.com, u-kumar1@ti.com,
        vigneshr@ti.com, nm@ti.com, martyn.welch@collabora.com
Subject: Re: [PATCH v7 10/13] media: ti: Add CSI2RX support for J721E
Message-ID: <20230324181425.GM18895@pendragon.ideasonboard.com>
References: <20230314115516.667-1-vaishnav.a@ti.com>
 <20230314115516.667-11-vaishnav.a@ti.com>
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In-Reply-To: <20230314115516.667-11-vaishnav.a@ti.com>
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Hi Vaishnav,

Thank you for the patch.

On Tue, Mar 14, 2023 at 05:25:13PM +0530, Vaishnav Achath 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>
> Signed-off-by: Jai Luthra <j-luthra@ti.com>
> Signed-off-by: Vaishnav Achath <vaishnav.a@ti.com>
> ---
> 
> Changes in v7:
> - Fix incorrect value written in SHIM_PSI_CFG0_DST_TAG
> - Drop support for 2X8 formats.
> - Update maintainer to Vaishnav as Pratyush moved out of TI.
> - Address Sakari's review comments:
> - Update MAX_HEIGHT_LINES, MAX_WIDTH_BYTES to prevent overflow.
> - Assign dma_slave_config during declaration, drop memset().
> - dma_release_channel() on slave_config failure.
> - provide entity ops for the vdev entity with link_validate().
> - mutex_destroy() on ti_csi2rx_probe failure path.
> - Drop busy check in remove().
> - mutex_destroy() in ti_csi2rx_remove().
> - Address Laurent's review comments:
> - Update entries in Makefile in alphabetical order.
> - include headers in alphabetical order.
> - Drop redundant CSI DT defines and use from media/mipi-csi2.h.
> - Rename csi_df to csi_dt.
> - Drop v4l2_colorspace from ti_csi2rx_fmt and set default in
>   ti_csi2rx_v4l2_init()
> - Adjust field and not return EINVAL in ti_csi2rx_try_fmt_vid_cap().
> - inline ti_csi2rx_video_register().
> - start DMA before starting source subdev.
> - move buffer cleanup to separate function ti_csi2rx_cleanup_buffers()
>   to be used in ti_csi2rx_stop_streaming() and ti_csi2rx_start_streaming()
>   failure path.
> - Drop VB2_USERPTR, VB2_READ and V4L2_CAP_READWRITE.
> 
> Changes in v5:
> - Add dependency on PHY_CADENCE_DPHY_RX instead of PHY_CADENCE_DPHY
>   since the Rx mode DPHY now has a separate driver.
> - Drop ti_csi2rx_validate_pipeline(). Pipeline validation should be done
>   at media_pipeline_start().
> - Do not assign flags.
> - Fix error handling in ti_csi2rx_start_streaming(). Free up vb2 buffers
>   when media_pipeline_start() fails.
> 
> Changes in v4:
> - Acquire the media device's graph_mutex before starting the graph walk.
> - Call media_graph_walk_init() and media_graph_walk_cleanup() when
>   starting and ending the graph walk respectively.
> - Reduce max frame height and width in enum_framesizes. Currently they
>   are set to UINT_MAX but they must be a multiple of step_width, so they
>   need to be rounded down. Also, these values are absurdly large which
>   causes some userspace applications like gstreamer to trip up. While it
>   is not generally right to change the kernel for an application bug, it
>   is not such a big deal here. This change is replacing one set of
>   absurdly large arbitrary values with another set of smaller but still
>   absurdly large arbitrary values. Both limits are unlikely to be hit in
>   practice.
> 
> Changes in v3:
> - Move DMA related fields in struct ti_csi2rx_dma.
> - Protect DMA buffer queue with a spinlock to make sure the queue buffer
>   and DMA callback don't race on it.
> - Track the current DMA state. It might go idle because of a lack of
>   buffers. This state can be used to restart it if needed.
> - Do not include the current buffer in the pending queue. It is slightly
>   better modelling than leaving it at the head of the pending queue.
> - Use the buffer as the callback argument, and add a reference to csi in it.
> - If queueing a buffer to DMA fails, the buffer gets leaked and DMA gets
>   stalled with. Instead, report the error to vb2 and queue the next
>   buffer in the pending queue.
> - DMA gets stalled if we run out of buffers since the callback is the
>   only one that fires subsequent transfers and it is no longer being
>   called. Check for that when queueing buffers and restart DMA if
>   needed.
> - Do not put of node until we are done using the fwnode.
> - Set inital format to UYVY 640x480.
> 
> Changes in v2:
> - Use dmaengine_get_dma_device() instead of directly accessing
>   dma->device->dev.
> - Do not set dst_addr_width when configuring slave DMA.
> - Move to a separate subdir and rename to j721e-csi2rx.c
> - Convert compatible to ti,j721e-csi2rx.
> - Move to use Media Controller centric APIs.
> - Improve cleanup in probe when one of the steps fails.
> - Add colorspace to formats database.
> - Set hw_revision on media_device.
> - Move video device initialization to probe time instead of register time.
> 
>  MAINTAINERS                                   |    6 +
>  drivers/media/platform/ti/Kconfig             |   12 +
>  drivers/media/platform/ti/Makefile            |    1 +
>  .../media/platform/ti/j721e-csi2rx/Makefile   |    2 +
>  .../platform/ti/j721e-csi2rx/j721e-csi2rx.c   | 1022 +++++++++++++++++
>  5 files changed, 1043 insertions(+)
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/Makefile
>  create mode 100644 drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 2892858cb040..69c2b0f48073 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20901,6 +20901,12 @@ S:	Odd Fixes
>  F:	drivers/clk/ti/
>  F:	include/linux/clk/ti.h
>  
> +TI J721E CSI2RX DRIVER
> +M:	Vaishnav Achath <vaishnav.a@ti.com>
> +L:	linux-media@vger.kernel.org
> +S:	Supported
> +F:	drivers/media/platform/ti/j721e-csi2rx/
> +
>  TI DAVINCI MACHINE SUPPORT
>  M:	Bartosz Golaszewski <brgl@bgdev.pl>
>  L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
> 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
> +	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..0c8dad049f5b
> --- /dev/null
> +++ b/drivers/media/platform/ti/j721e-csi2rx/j721e-csi2rx.c
> @@ -0,0 +1,1022 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * TI CSI2 RX driver.
> + *
> + * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
> + *
> + * Author: Pratyush Yadav <p.yadav@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/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_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_PSI_CFG0			0x24
> +#define SHIM_PSI_CFG0_SRC_TAG		GENMASK(15, 0)
> +#define SHIM_PSI_CFG0_DST_TAG		GENMASK(31, 15)
> +
> +#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
> +
> +struct ti_csi2rx_fmt {
> +	u32				fourcc;	/* Four character code. */
> +	u32				code;	/* Mbus code. */
> +	u32				csi_dt;	/* CSI Data type. */
> +	u8				bpp;	/* Bits per pixel. */
> +};
> +
> +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;
> +	/*
> +	 * Current buffer being processed by DMA. NULL if no buffer is being
> +	 * processed.
> +	 */
> +	struct ti_csi2rx_buffer		*curr;
> +};
> +
> +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		*subdev;
> +	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[] = {
> +	{
> +		.fourcc			= V4L2_PIX_FMT_YUYV,
> +		.code			= MEDIA_BUS_FMT_YUYV8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_UYVY,
> +		.code			= MEDIA_BUS_FMT_UYVY8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_YVYU,
> +		.code			= MEDIA_BUS_FMT_YVYU8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +	}, {
> +		.fourcc			= V4L2_PIX_FMT_VYUY,
> +		.code			= MEDIA_BUS_FMT_VYUY8_1X16,
> +		.csi_dt			= MIPI_CSI2_DT_YUV422_8B,
> +		.bpp			= 16,
> +	},
> +
> +	/* More formats can be supported but they are not listed for now. */
> +};
> +
> +static const unsigned int num_formats = ARRAY_SIZE(formats);
> +
> +/* 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)
> +{
> +	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 = csi_fmt->bpp;
> +	u32 bpl;
> +
> +	/* TODO: Figure this out. */

Figure what out ? :-) Please expand this comment to explain what needs
to be done.

> +
> +	pixels_in_word = PSIL_WORD_SIZE_BYTES * 8 / bpp;
> +
> +	pix->width = clamp_t(unsigned int, pix->width,
> +			     pixels_in_word,
> +			     MAX_WIDTH_BYTES * 8 / bpp);
> +	pix->width = rounddown(pix->width, pixels_in_word);
> +
> +	pix->height = clamp_t(unsigned int, pix->height, 1, MAX_HEIGHT_LINES);
> +
> +	v4l2_fmt->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	pix->pixelformat = csi_fmt->fourcc;
> +	pix->colorspace = V4L2_COLORSPACE_SRGB;
> +	pix->sizeimage = pix->height * pix->width * (bpp / 8);
> +
> +	bpl = (pix->width * ALIGN(bpp, 8)) >> 3;
> +	pix->bytesperline = ALIGN(bpl, 16);
> +}
> +
> +static int ti_csi2rx_querycap(struct file *file, void *priv,
> +			      struct v4l2_capability *cap)
> +{
> +	struct ti_csi2rx_dev *csi = video_drvdata(file);
> +
> +	strscpy(cap->driver, TI_CSI2RX_MODULE_NAME, sizeof(cap->driver));
> +	strscpy(cap->card, TI_CSI2RX_MODULE_NAME, sizeof(cap->card));
> +
> +	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:%s",
> +		 dev_name(csi->dev));

https://lore.kernel.org/linux-media/20220122163656.168440-1-sakari.ailus@linux.intel.com/
has been merged in v5.19, so you don't need to set bus_info manually
anymore.

> +
> +	return 0;
> +}
> +
> +static int ti_csi2rx_enum_fmt_vid_cap(struct file *file, void *priv,
> +				      struct v4l2_fmtdesc *f)
> +{
> +	if (f->index >= num_formats)
> +		return -EINVAL;
> +
> +	memset(f->reserved, 0, sizeof(f->reserved));
> +	f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	f->pixelformat = formats[f->index].fourcc;
> +
> +	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];
> +
> +	if (f->fmt.pix.field == V4L2_FIELD_ANY)
> +		f->fmt.pix.field = V4L2_FIELD_NONE;
> +
> +	if (f->fmt.pix.field != V4L2_FIELD_NONE)
> +		/* 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)
> +		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 inline int ti_csi2rx_video_register(struct ti_csi2rx_dev *csi)

You can drop the "inline" keyword, the compiler will inline the function
automatically if it believes it makes sense.

> +{
> +	struct video_device *vdev = &csi->vdev;
> +	int ret, src_pad;
> +
> +	ret = video_register_device(vdev, VFL_TYPE_VIDEO, -1);
> +	if (ret)
> +		return ret;
> +
> +	src_pad = media_entity_get_fwnode_pad(&csi->subdev->entity,
> +					      csi->subdev->fwnode,
> +					      MEDIA_PAD_FL_SOURCE);
> +	if (src_pad < 0) {
> +		dev_err(csi->dev, "Couldn't find source pad for subdev\n");
> +		return src_pad;
> +	}
> +
> +	ret = media_create_pad_link(&csi->subdev->entity, src_pad,
> +				    &vdev->entity, 0,
> +				    MEDIA_LNK_FL_IMMUTABLE |
> +				    MEDIA_LNK_FL_ENABLED);
> +	if (ret) {
> +		video_unregister_device(vdev);
> +		return ret;
> +	}

I've sent a patch that makes v4l2_create_fwnode_links_to_pad() usable
when the sink is not a subdev. Could you test it to see if it can
simplify this function ?

> +
> +	return 0;
> +}
> +
> +static int csi_async_notifier_bound(struct v4l2_async_notifier *notifier,
> +				    struct v4l2_subdev *subdev,
> +				    struct v4l2_async_subdev *asd)
> +{
> +	struct ti_csi2rx_dev *csi = dev_get_drvdata(notifier->v4l2_dev->dev);
> +
> +	csi->subdev = 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);
> +	int ret;
> +
> +	ret = ti_csi2rx_video_register(csi);

I commented on the previous version with

  I would inline the ti_csi2rx_video_register() function here, it's not
  large, and it's only called in a single place.

which I assume you've understood as asking for the "inline" keyword
above. What I meant was to take the contents of the
ti_csi2rx_video_register() function and move them into this function.

> +	if (ret)
> +		return ret;
> +
> +	return v4l2_device_register_subdev_nodes(&csi->v4l2_dev);
> +}
> +
> +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_init_subdev(struct ti_csi2rx_dev *csi)
> +{
> +	struct fwnode_handle *fwnode;
> +	struct v4l2_async_subdev *asd;
> +	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->notifier.ops = &csi_async_notifier_ops;
> +
> +	asd = v4l2_async_nf_add_fwnode(&csi->notifier, fwnode,
> +				       struct v4l2_async_subdev);
> +	of_node_put(node);
> +	if (IS_ERR(asd)) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return PTR_ERR(asd);
> +	}
> +
> +	ret = v4l2_async_nf_register(&csi->v4l2_dev, &csi->notifier);
> +	if (ret) {
> +		v4l2_async_nf_cleanup(&csi->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void 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, "Unknown format\n");
> +		return;
> +	}
> +
> +	/* 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;
> +	}
> +
> +	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);
> +}
> +
> +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;
> +
> +	buf->vb.vb2_buf.timestamp = ktime_get_ns();
> +	buf->vb.sequence = csi->sequence++;

In a reply to the previous version, Pratyush mentioned that there is a
register in the CSI2RX core that provides the frame number. While it may
not be very straightforward to get the information from there, it would
still be desirable. Could you please add a TODO comment to record this ?

	/*
	 * TODO: Derive the sequence number from the CSI2RX frame number
	 * hardware register.
	 */

> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +
> +	WARN_ON(dma->curr != buf);
> +	vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_DONE);
> +
> +	/* If there are more buffers to process then start their transfer. */
> +	dma->curr = NULL;
> +	while (!list_empty(&dma->queue)) {
> +		buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +		list_del(&buf->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 {
> +			dma->curr = buf;
> +			break;

In the same reply, Pratyush also mentioned that all pending buffers
should be queued to the DMA engine here.

> +		}
> +	}
> +
> +	if (!dma->curr)
> +		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 state)
> +{
> +	struct ti_csi2rx_dma *dma = &csi->dma;
> +	struct ti_csi2rx_buffer *buf = NULL, *tmp;

No need to initialize buf to NULL.

> +	unsigned long flags;
> +
> +	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, state);
> +	}
> +
> +	if (dma->curr)
> +		vb2_buffer_done(&dma->curr->vb.vb2_buf, state);
> +
> +	dma->curr = NULL;
> +	dma->state = TI_CSI2RX_DMA_STOPPED;
> +	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;
> +	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) {
> +		ret = ti_csi2rx_start_dma(csi, buf);
> +		if (ret) {
> +			dev_err(csi->dev, "Failed to start DMA: %d\n", ret);
> +			vb2_buffer_done(&buf->vb.vb2_buf, VB2_BUF_STATE_QUEUED);
> +			goto unlock;
> +		}
> +
> +		dma->curr = buf;
> +		dma->state = TI_CSI2RX_DMA_ACTIVE;
> +	} else {
> +		list_add_tail(&buf->list, &dma->queue);
> +	}
> +
> +unlock:
> +	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;
> +
> +	ret = media_pipeline_start(&csi->vdev.entity.pads[0], &csi->pipe);

Please use the video_device_pipeline_start() helper for video nodes.
Same for media_pipeline_stop(), there's now
video_device_pipeline_stop().

> +	if (ret)
> +		goto err;
> +
> +	ti_csi2rx_setup_shim(csi);
> +
> +	csi->sequence = 0;
> +
> +	spin_lock_irqsave(&dma->lock, flags);
> +	buf = list_entry(dma->queue.next, struct ti_csi2rx_buffer, list);
> +	list_del(&buf->list);
> +	dma->state = TI_CSI2RX_DMA_ACTIVE;
> +	dma->curr = buf;
> +
> +	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;
> +	}
> +
> +	spin_unlock_irqrestore(&dma->lock, flags);
> +
> +	ret = v4l2_subdev_call(csi->subdev, 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:
> +	media_pipeline_stop(&csi->vdev.entity.pads[0]);
> +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;
> +
> +	media_pipeline_stop(&csi->vdev.entity.pads[0]);
> +
> +	ret = v4l2_subdev_call(csi->subdev, video, s_stream, 0);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop subdev stream\n");
> +
> +	writel(0, csi->shim + SHIM_CNTL);
> +
> +	ret = dmaengine_terminate_sync(csi->dma.chan);
> +	if (ret)
> +		dev_err(csi->dev, "Failed to stop DMA: %d\n", ret);
> +
> +	writel(0, csi->shim + SHIM_DMACNTX);
> +
> +	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 | VB2_READ;

Support for VB2_READ is not recommended as it's very inefficient. Please
drop it.

> +	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_get_fmt(struct media_pad *pad,
> +					   struct v4l2_subdev_format *fmt)
> +{
> +	if (is_media_entity_v4l2_subdev(pad->entity)) {
> +		struct v4l2_subdev *sd =
> +			media_entity_to_v4l2_subdev(pad->entity);
> +
> +		fmt->which = V4L2_SUBDEV_FORMAT_ACTIVE;
> +		fmt->pad = pad->index;
> +		return v4l2_subdev_call(sd, pad, get_fmt, NULL, fmt);

This will crash with any source that uses the subdev active state. You
can't pass NULL for the state here.

How about exporting v4l2_subdev_link_validate_get_format() instead, to
replace this function ?

> +	}
> +
> +	WARN(pad->entity->function != MEDIA_ENT_F_IO_V4L,
> +	     "Driver bug! Wrong media entity type 0x%08x, entity %s\n",
> +	     pad->entity->function, pad->entity->name);
> +
> +	return -EINVAL;
> +}
> +
> +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;
> +	const struct ti_csi2rx_fmt *ti_fmt;
> +	int ret;
> +
> +	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
> +		dev_info(csi->dev, "video node %s pad not connected\n",
> +			 vdev->name);
> +		return -ENOTCONN;
> +	}

This can't happen, __media_pipeline_start() skips links that are not
enabled before calling .link_validate().

> +
> +	ret = ti_csi2rx_link_validate_get_fmt(link->source, &source_fmt);
> +	if (ret)
> +		return ret;
> +
> +	if (source_fmt.format.width != csi_fmt->width) {
> +		dev_err(csi->dev, "Width does not match (source %u, sink %u)\n",
> +			source_fmt.format.width, csi_fmt->width);

Make it dev_dbg(), we don't want to output error messages in the kernel
log for something that can be easily triggered by userspace. Same below.

> +		return -EPIPE;
> +	}
> +
> +	if (source_fmt.format.height != csi_fmt->height) {
> +		dev_err(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_err(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_err(csi->dev, "Media bus format 0x%x not supported\n",
> +			source_fmt.format.code);
> +		return -EPIPE;
> +	}
> +
> +	if (source_fmt.format.code == MEDIA_BUS_FMT_YUYV8_2X8 ||
> +	    source_fmt.format.code == MEDIA_BUS_FMT_VYUY8_2X8 ||
> +	    source_fmt.format.code == MEDIA_BUS_FMT_YVYU8_2X8) {

Those three formats are not listed in the ti_csi2rx_fmt formats array,
so find_format_by_code() will have returned NULL already, and this check
can never be true.

> +		dev_err(csi->dev,
> +			"Only UYVY input allowed for YUV422 8-bit. Output format can be configured.\n");
> +		return -EPIPE;
> +	}
> +
> +	if (source_fmt.format.code != ti_fmt->code) {

That can never be true, as ti_fmt is looked up based on
source_fmt.format.code. Did you mean to check if ti_fmt->fourcc ==
csi->v_fmt.fmt.pix.pixelformat ?

> +		dev_err(csi->dev,
> +			"Cannot transform source fmt 0x%x to sink fmt 0x%x\n",
> +			source_fmt.format.code, ti_fmt->code);
> +		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 };

	struct dma_slave_config cfg = {
		.src_addr_width = DMA_SLAVE_BUSWIDTH_16_BYTES,
	};

> +	int ret;
> +
> +	INIT_LIST_HEAD(&csi->dma.queue);
> +	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));
> +	snprintf(mdev->bus_info, sizeof(mdev->bus_info), "platform:%s",
> +		 dev_name(mdev->dev));

You can drop manual setting of bus_info here too.

> +
> +	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_init_subdev(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", },
> +	{ },
> +};
> +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