Date:   Tue, 2 Nov 2021 18:22:36 +0100
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Eugen Hristev <eugen.hristev@...rochip.com>
Cc:     linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        laurent.pinchart@...asonboard.com, sakari.ailus@....fi,
        robh+dt@...nel.org, nicolas.ferre@...rochip.com
Subject: Re: [PATCH 03/21] media: atmel: introduce microchip csi2dc driver

Hi Eugen,

On Fri, Oct 22, 2021 at 10:52:29AM +0300, Eugen Hristev wrote:
> Microchip CSI2DC (CSI2 Demultiplexer Controller) is a misc bridge device
> that converts a byte stream in IDI Synopsys format (coming from a CSI2HOST)
> to a pixel stream that can be captured by a sensor controller.
>
> Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
> ---
> Changes in this revision:
> - addressed comments by Jacopo and Laurent as in this thread:
> https://www.spinics.net/lists/linux-media/msg181044.html
>
> Previous change log :
> Changes in v5:
> - only in bindings
>
> Changes in v4:
> - now using get_mbus_config ops to get data from the subdevice, like the
> virtual channel id, and the clock type.
> - now having possibility to select any of the RAW10 data modes
> - at completion time, select which formats are also available in the subdevice,
> and move to the dynamic list accordingly
> - changed the pipeline integration, do not advertise subdev ready at probe time.
> wait until completion is done, and then start a workqueue that will register
> this device as a subdevice for the next element in pipeline.
> - moved the s_power code into a different function called now csi2dc_power
> that is called with CONFIG_PM functions. This is also called at completion,
> to have the device ready in case CONFIG_PM is not selected on the platform.
> - merged try_fmt into set_fmt
> - driver cleanup, wrapped lines over 80 characters
>
> Changes in v2:
> - moved driver to platform/atmel
> - fixed minor things as per Sakari's review
> - still some things from v2 review are not yet addressed, to be followed up
>
>
>  drivers/media/platform/atmel/Kconfig          |  15 +
>  drivers/media/platform/atmel/Makefile         |   1 +
>  .../media/platform/atmel/microchip-csi2dc.c   | 700 ++++++++++++++++++
>  3 files changed, 716 insertions(+)
>  create mode 100644 drivers/media/platform/atmel/microchip-csi2dc.c
>
> diff --git a/drivers/media/platform/atmel/Kconfig b/drivers/media/platform/atmel/Kconfig
> index dda2f27da317..f83bee373d82 100644
> --- a/drivers/media/platform/atmel/Kconfig
> +++ b/drivers/media/platform/atmel/Kconfig
> @@ -40,3 +40,18 @@ config VIDEO_ATMEL_ISI
>  	help
>  	  This module makes the ATMEL Image Sensor Interface available
>  	  as a v4l2 device.
> +
> +config VIDEO_MICROCHIP_CSI2DC
> +	tristate "Microchip CSI2 Demux Controller"
> +	depends on VIDEO_V4L2 && COMMON_CLK && OF
> +	depends on ARCH_AT91 || COMPILE_TEST
> +	select MEDIA_CONTROLLER
> +	select VIDEO_V4L2_SUBDEV_API
> +	select V4L2_FWNODE
> +	help
> +	  CSI2 Demux Controller driver. CSI2DC is a helper chip
> +	  that converts IDI interface byte stream to a parallel pixel stream.
> +	  It supports various RAW formats as input.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called microchip-csi2dc.
> diff --git a/drivers/media/platform/atmel/Makefile b/drivers/media/platform/atmel/Makefile
> index 46d264ab7948..39f0a7eba702 100644
> --- a/drivers/media/platform/atmel/Makefile
> +++ b/drivers/media/platform/atmel/Makefile
> @@ -6,3 +6,4 @@ obj-$(CONFIG_VIDEO_ATMEL_ISI) += atmel-isi.o
>  obj-$(CONFIG_VIDEO_ATMEL_ISC_BASE) += atmel-isc-base.o
>  obj-$(CONFIG_VIDEO_ATMEL_ISC) += atmel-isc.o
>  obj-$(CONFIG_VIDEO_ATMEL_XISC) += atmel-xisc.o
> +obj-$(CONFIG_VIDEO_MICROCHIP_CSI2DC) += microchip-csi2dc.o
> diff --git a/drivers/media/platform/atmel/microchip-csi2dc.c b/drivers/media/platform/atmel/microchip-csi2dc.c
> new file mode 100644
> index 000000000000..277b86988eee
> --- /dev/null
> +++ b/drivers/media/platform/atmel/microchip-csi2dc.c
> @@ -0,0 +1,700 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Microchip CSI2 Demux Controller (CSI2DC) driver
> + *
> + * Copyright (C) 2018 Microchip Technology, Inc.
> + *
> + * Author: Eugen Hristev <eugen.hristev@...rochip.com>
> + *
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/module.h>
> +#include <linux/of.h>

Isn't linux/mod_devicetable.h enough ?

> +#include <linux/of_graph.h>

You should probably move to use the fwnode_graph framwork instead of
of_graph. This driver depends on OF so it shouldn't be an issue but I
defer this to maintainers

> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/videodev2.h>
> +
> +#include <media/v4l2-device.h>

Do you need this include ?

> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +#include <media/videobuf2-dma-contig.h>

Is this one needed as well ?

> +
> +/* Global configuration register */
> +#define CSI2DC_GCFG			0x0
> +
> +/* MIPI sensor pixel clock is free running */
> +#define CSI2DC_GCFG_MIPIFRN		BIT(0)
> +/* Output waveform inter-line minimum delay */
> +#define CSI2DC_GCFG_HLC(v)		((v) << 4)
> +#define CSI2DC_GCFG_HLC_MASK		GENMASK(7, 4)
> +/* SAMA7G5 requires a HLC delay of 15 */
> +#define SAMA7G5_HLC			(15)
> +
> +/* Global control register */
> +#define CSI2DC_GCTLR			0x04
> +#define CSI2DC_GCTLR_SWRST		BIT(0)
> +
> +/* Global status register */
> +#define CSI2DC_GS			0x08
> +
> +/* SSP interrupt status register */
> +#define CSI2DC_SSPIS			0x28
> +/* Pipe update register */
> +#define CSI2DC_PU			0xC0

What about using lowercase for hex values (I know there's not strict
rule, so keep what you like the most, but most drivers use lowercase

> +/* Video pipe attributes update */
> +#define CSI2DC_PU_VP			BIT(0)
> +
> +/* Pipe update status register */
> +#define CSI2DC_PUS			0xC4
> +
> +/* Video pipeline enable register */
> +#define CSI2DC_VPE			0xF8
> +#define CSI2DC_VPE_ENABLE		BIT(0)
> +
> +/* Video pipeline configuration register */
> +#define CSI2DC_VPCFG			0xFC
> +/* Data type */
> +#define CSI2DC_VPCFG_DT(v)		((v) << 0)
> +#define CSI2DC_VPCFG_DT_MASK		GENMASK(5, 0)
> +/* Virtual channel identifier */
> +#define CSI2DC_VPCFG_VC(v)		((v) << 6)
> +#define CSI2DC_VPCFG_VC_MASK		GENMASK(7, 6)
> +/* Decompression enable */
> +#define CSI2DC_VPCFG_DE			BIT(8)
> +/* Decoder mode */
> +#define CSI2DC_VPCFG_DM(v)		((v) << 9)
> +#define CSI2DC_VPCFG_DM_DECODER8TO12	0
> +/* Decoder predictor 2 selection */
> +#define CSI2DC_VPCFG_DP2		BIT(12)
> +/* Recommended memory storage */
> +#define CSI2DC_VPCFG_RMS		BIT(13)
> +/* Post adjustment */
> +#define CSI2DC_VPCFG_PA			BIT(14)
> +
> +/* Video pipeline column register */
> +#define CSI2DC_VPCOL			0x100
> +/* Column number */
> +#define CSI2DC_VPCOL_COL(v)		((v) << 0)
> +#define CSI2DC_VPCOL_COL_MASK		GENMASK(15, 0)
> +
> +/* Video pipeline row register */
> +#define CSI2DC_VPROW			0x104
> +/* Row number */
> +#define CSI2DC_VPROW_ROW(v)		((v) << 0)
> +#define CSI2DC_VPROW_ROW_MASK		GENMASK(15, 0)
> +
> +/* Version register */
> +#define CSI2DC_VERSION			0x1FC
> +
> +/* register read/write helpers */
> +#define csi2dc_readl(st, reg)		readl_relaxed((st)->base + (reg))
> +#define csi2dc_writel(st, reg, val)	writel_relaxed((val), \
> +					(st)->base + (reg))
> +
> +/* supported RAW data types */
> +#define CSI2DC_DT_RAW6			0x28
> +#define CSI2DC_DT_RAW7			0x29
> +#define CSI2DC_DT_RAW8			0x2A
> +#define CSI2DC_DT_RAW10			0x2B
> +#define CSI2DC_DT_RAW12			0x2C
> +#define CSI2DC_DT_RAW14			0x2D
> +
> +/*
> + * struct csi2dc_format - CSI2DC format type struct
> + * @mbus_code:		Media bus code for the format
> + * @dt:			Data type constant for this format
> + */
> +struct csi2dc_format {
> +	u32				mbus_code;
> +	u32				dt;
> +};
> +
> +static const struct csi2dc_format csi2dc_formats[] = {
> +	{
> +		.mbus_code =		MEDIA_BUS_FMT_SRGGB10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	}, {
> +		.mbus_code =		MEDIA_BUS_FMT_SBGGR10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	}, {
> +		.mbus_code =		MEDIA_BUS_FMT_SGRBG10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	}, {
> +		.mbus_code =		MEDIA_BUS_FMT_SGBRG10_1X10,
> +		.dt =			CSI2DC_DT_RAW10,
> +	},
> +};

How unfortunate we don't have this in the core...

> +
> +enum mipi_csi_pads {
> +	CSI2DC_PAD_SINK			= 0,
> +	CSI2DC_PAD_SOURCE		= 1,
> +	CSI2DC_PADS_NUM			= 2,
> +};
> +
> +/*
> + * struct csi2dc_device - CSI2DC device driver data/config struct
> + * @base:		Register map base address
> + * @csi2dc_sd:		v4l2 subdevice for the csi2dc device
> + *			This is the subdevice that the csi2dc device itself
> + *			registers in v4l2 subsystem
> + * @dev:		struct device for this csi2dc device
> + * @pclk:		Peripheral clock reference
> + *			Input clock that clocks the hardware block internal
> + *			logic
> + * @scck:		Sensor Controller clock reference
> + *			Input clock that is used to generate the pixel clock
> + * @format:		Current saved format used in g/s fmt
> + * @cur_fmt:		Current state format
> + * @try_fmt:		Try format that is being tried
> + * @pads:		Media entity pads for the csi2dc subdevice
> + * @clk_gated:		Whether the clock is gated or free running
> + * @video_pipe:		Whether video pipeline is configured
> + * @vc:			Current set virtual channel
> + * @asd:		Async subdevice for async bound of the underlying subdev
> + * @notifier:		Async notifier that is used to bound the underlying
> + *			subdevice to the csi2dc subdevice
> + * @input_sd:		Reference to the underlying subdevice bound to the
> + *			csi2dc subdevice
> + * @remote_pad:		Pad number of the underlying subdevice that is linked
> + *			to the csi2dc subdevice sink pad.
> + */
> +struct csi2dc_device {
> +	void __iomem			*base;
> +	struct v4l2_subdev		csi2dc_sd;
> +	struct device			*dev;
> +	struct clk			*pclk;
> +	struct clk			*scck;
> +
> +	struct v4l2_mbus_framefmt	 format;
> +
> +	const struct csi2dc_format	*cur_fmt;
> +	const struct csi2dc_format	*try_fmt;
> +
> +	struct media_pad		pads[CSI2DC_PADS_NUM];
> +
> +	bool				clk_gated;
> +	bool				video_pipe;
> +	u32				vc;
> +
> +	struct v4l2_async_subdev	*asd;
> +	struct v4l2_async_notifier	notifier;
> +
> +	struct v4l2_subdev		*input_sd;
> +
> +	u32				remote_pad;
> +};
> +
> +static void csi2dc_vp_update(struct csi2dc_device *csi2dc)

Could you move this below closer to the only caller ?

> +{
> +	u32 vp;
> +
> +	if (!csi2dc->cur_fmt) {

You should probably initialize this to a default format

> +		dev_err(csi2dc->dev, "format must be configured first\n");
> +		return;
> +	}
> +
> +	if (!csi2dc->video_pipe) {

This is only called internally by the driver at s_stream() time, can
this happen ? Or rather won't you have a streamon call also when the
data pipe only is available ? In that case you would error out here

> +		dev_err(csi2dc->dev, "video pipeline unavailable\n");
> +		return;
> +	}
> +
> +	vp = CSI2DC_VPCFG_DT(csi2dc->cur_fmt->dt) & CSI2DC_VPCFG_DT_MASK;
> +	vp |= CSI2DC_VPCFG_VC(csi2dc->vc) & CSI2DC_VPCFG_VC_MASK;
> +	vp &= ~CSI2DC_VPCFG_DE;
> +	vp |= CSI2DC_VPCFG_DM(CSI2DC_VPCFG_DM_DECODER8TO12);
> +	vp &= ~CSI2DC_VPCFG_DP2;
> +	vp &= ~CSI2DC_VPCFG_RMS;
> +	vp |= CSI2DC_VPCFG_PA;
> +
> +	csi2dc_writel(csi2dc, CSI2DC_VPCFG, vp);
> +	csi2dc_writel(csi2dc, CSI2DC_VPE, CSI2DC_VPE_ENABLE);
> +	csi2dc_writel(csi2dc, CSI2DC_PU, CSI2DC_PU_VP);
> +}
> +
> +static inline struct csi2dc_device *
> +csi2dc_sd_to_csi2dc_device(struct v4l2_subdev *csi2dc_sd)
> +{
> +	return container_of(csi2dc_sd, struct csi2dc_device, csi2dc_sd);
> +}
> +
> +static int csi2dc_enum_mbus_code(struct v4l2_subdev *csi2dc_sd,
> +				 struct v4l2_subdev_state *sd_state,
> +				 struct v4l2_subdev_mbus_code_enum *code)
> +{
> +	if (code->index >= ARRAY_SIZE(csi2dc_formats))
> +		return -EINVAL;
> +
> +	code->code = csi2dc_formats[code->index].mbus_code;
> +
> +	return 0;
> +}
> +
> +static int csi2dc_get_fmt(struct v4l2_subdev *csi2dc_sd,
> +			  struct v4l2_subdev_state *sd_state,
> +			  struct v4l2_subdev_format *format)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +
> +	format->format = csi2dc->format;
> +
> +	return 0;

You should support try formats by storing the format in the file
handle state in s_fmt and return it in case which == TRY

Grep for v4l2_subdev_get_try_format() for usage examples

> +}
> +
> +static int csi2dc_set_fmt(struct v4l2_subdev *csi2dc_sd,
> +			  struct v4l2_subdev_state *sd_state,
> +			  struct v4l2_subdev_format *req_fmt)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +	const struct csi2dc_format *fmt;
> +	int i;

unsigned

> +
> +	for (i = 0; i < ARRAY_SIZE(csi2dc_formats);  i++) {
> +		fmt = &csi2dc_formats[i];
> +		if (req_fmt->format.code == fmt->mbus_code)
> +			csi2dc->try_fmt = fmt;

Shouldn't you break ?

> +		fmt++;
> +	}

And make this a simpler

        for (i = 0; i < ARRAY_SIZE(csi2dc_formats); i++) {
                if (req_fmt->format.code == csi2dc_formats[i].mbus_code)
                        break;
        }

        if (i == ARRAY_SIZE(csi2dc_formats)
                i = 0;

> +
> +	/* in case we could not find the desired format, default to something */
> +	if (!csi2dc->try_fmt  ||
> +	    req_fmt->format.code != csi2dc->try_fmt->mbus_code) {
> +		csi2dc->try_fmt = &csi2dc_formats[0];
> +
> +		dev_dbg(csi2dc->dev,
> +			"CSI2DC unsupported format 0x%x, defaulting to 0x%x\n",
> +			req_fmt->format.code, csi2dc_formats[0].mbus_code);
> +
> +		req_fmt->format.code = csi2dc_formats[0].mbus_code;
> +	}
> +
> +	req_fmt->format.colorspace = V4L2_COLORSPACE_SRGB;
> +	req_fmt->format.field = V4L2_FIELD_NONE;
> +
> +	/* save the format for later requests */

You should support TRY formats

> +	csi2dc->format = req_fmt->format;
> +
> +	/* if we are just trying, we are done */
> +	if (req_fmt->which == V4L2_SUBDEV_FORMAT_TRY)
> +		return 0;
> +
> +	csi2dc->cur_fmt = csi2dc->try_fmt;

        csi2dc->cur_fmt = &csi2dc_format[i];

So you can drop the try_fmt from the driver structure as it seems to
be used as a temporary variable here only.

> +
> +	dev_dbg(csi2dc->dev, "new format set: 0x%x\n", req_fmt->format.code);
> +
> +	return 0;
> +}
> +
> +static int csi2dc_power(struct csi2dc_device *csi2dc, int on)
> +{
> +	int ret = 0;
> +
> +	if (on) {
> +		ret = clk_prepare_enable(csi2dc->pclk);
> +		if (ret) {
> +			dev_err(csi2dc->dev, "failed to enable pclk: %d\n", ret);
> +			return ret;
> +		}
> +
> +		ret = clk_prepare_enable(csi2dc->scck);
> +		if (ret)
> +			dev_err(csi2dc->dev,
> +				"failed to enable scck: %d\n", ret);

Shouldn't you bail out here ?

> +
> +		/* if powering up, deassert reset line */
> +		csi2dc_writel(csi2dc, CSI2DC_GCTLR, CSI2DC_GCTLR_SWRST);
> +	} else {
> +		clk_disable_unprepare(csi2dc->scck);
> +
> +		/* if powering down, assert reset line */
> +		csi2dc_writel(csi2dc, CSI2DC_GCTLR, !CSI2DC_GCTLR_SWRST);

Isn't reverse order of activation better ?

                csi2dc_writel(..)
                clk_disable_unprepare(..)
                clk_disable_unprepare(..)
> +
> +		clk_disable_unprepare(csi2dc->pclk);
> +	}
> +
> +	return ret;
> +}
> +
> +static int csi2dc_s_stream(struct v4l2_subdev *csi2dc_sd, int enable)
> +{
> +	struct csi2dc_device *csi2dc = csi2dc_sd_to_csi2dc_device(csi2dc_sd);
> +	int ret;
> +
> +	if (enable) {
> +		ret = pm_runtime_resume_and_get(csi2dc->dev);
> +		if (ret < 0)
> +			return ret;
> +		csi2dc_vp_update(csi2dc);
> +	} else {
> +		pm_runtime_put_sync(csi2dc->dev);
> +	}
> +
> +	return v4l2_subdev_call(csi2dc->input_sd, video, s_stream, enable);

Should the remote subdev be started before and stopped after ?

> +}
> +
> +static const struct v4l2_subdev_pad_ops csi2dc_pad_ops = {
> +	.enum_mbus_code = csi2dc_enum_mbus_code,
> +	.set_fmt = csi2dc_set_fmt,
> +	.get_fmt = csi2dc_get_fmt,
> +};
> +
> +static const struct v4l2_subdev_video_ops csi2dc_video_ops = {
> +	.s_stream = csi2dc_s_stream,
> +};
> +
> +static const struct v4l2_subdev_ops csi2dc_subdev_ops = {
> +	.pad = &csi2dc_pad_ops,
> +	.video = &csi2dc_video_ops,
> +};
> +
> +static int csi2dc_get_mbus_config(struct csi2dc_device *csi2dc)
> +{
> +	struct v4l2_mbus_config mbus_config = { 0 };
> +	int ret;
> +
> +	ret = v4l2_subdev_call(csi2dc->input_sd, pad, get_mbus_config,
> +			       csi2dc->remote_pad, &mbus_config);
> +	if (ret == -ENOIOCTLCMD) {
> +		dev_dbg(csi2dc->dev,
> +			"no remote mbus configuration available\n");
> +		goto csi2dc_get_mbus_config_defaults;
> +	}
> +
> +	if (ret) {
> +		dev_err(csi2dc->dev,
> +			"failed to get remote mbus configuration\n");
> +		goto csi2dc_get_mbus_config_defaults;
> +	}
> +
> +	if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_0)
> +		csi2dc->vc = 0;
> +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_1)
> +		csi2dc->vc = 1;
> +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_2)
> +		csi2dc->vc = 2;
> +	else if (mbus_config.flags & V4L2_MBUS_CSI2_CHANNEL_3)
> +		csi2dc->vc = 3;
> +
> +	dev_dbg(csi2dc->dev, "subdev sending on channel %d\n", csi2dc->vc);
> +
> +	csi2dc->clk_gated = mbus_config.flags &
> +				V4L2_MBUS_CSI2_NONCONTINUOUS_CLOCK;

This should come from the default clock-noncontinuous property in the
endpoint. It is available in the mbus_configuration only to support
subdevs that can change it at runtime, and if that's the case it's ok,
but I think it should be in the endpoint.

Speaking of remote subdevs, is there any driver available for IDI
transmitters ?

> +
> +	dev_dbg(csi2dc->dev, "%s clock\n",
> +		csi2dc->clk_gated ? "gated" : "free running");
> +
> +	return 0;
> +
> +csi2dc_get_mbus_config_defaults:
> +	csi2dc->vc = 0; /* Virtual ID 0 by default */
> +	csi2dc->clk_gated = false; /* Free running clock by default */
> +
> +	return 0;
> +}
> +
> +static int csi2dc_async_bound(struct v4l2_async_notifier *notifier,
> +			      struct v4l2_subdev *subdev,
> +			      struct v4l2_async_subdev *asd)
> +{
> +	struct csi2dc_device *csi2dc = container_of(notifier,
> +						struct csi2dc_device, notifier);
> +	int pad;
> +	int ret;
> +
> +	csi2dc->input_sd = subdev;
> +
> +	pad = media_entity_get_fwnode_pad(&subdev->entity,

You can use 'ret'

> +					  asd->match.fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (pad < 0) {
> +		dev_err(csi2dc->dev, "Failed to find pad for %s\n",
> +			subdev->name);
> +		return pad;
> +	}
> +
> +	csi2dc->remote_pad = pad;
> +
> +	csi2dc_get_mbus_config(csi2dc);

Ideally, as this is not fatal, you could move this at s_stream time to
fetch the most up-to-date configuration

> +
> +	ret = media_create_pad_link(&csi2dc->input_sd->entity,
> +				    csi2dc->remote_pad,
> +				    &csi2dc->csi2dc_sd.entity, 0,
> +				    MEDIA_LNK_FL_ENABLED);
> +	if (ret < 0) {

        if (ret)

> +		dev_err(csi2dc->dev,
> +			"Failed to create pad link: %s to %s\n",
> +			csi2dc->input_sd->entity.name,
> +			csi2dc->csi2dc_sd.entity.name);
> +		return ret;
> +	}
> +
> +	dev_dbg(csi2dc->dev, "link with %s pad: %d\n",
> +		csi2dc->input_sd->name, csi2dc->remote_pad);
> +
> +	ret = pm_runtime_resume_and_get(csi2dc->dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	csi2dc_writel(csi2dc, CSI2DC_GCFG,
> +		      (SAMA7G5_HLC & CSI2DC_GCFG_HLC_MASK) |
> +		      (csi2dc->clk_gated ? 0 : CSI2DC_GCFG_MIPIFRN));
> +
> +	csi2dc_writel(csi2dc, CSI2DC_VPCOL,
> +		      CSI2DC_VPCOL_COL(0xFFF) & CSI2DC_VPCOL_COL_MASK);
> +	csi2dc_writel(csi2dc, CSI2DC_VPROW,
> +		      CSI2DC_VPROW_ROW(0xFFF) & CSI2DC_VPROW_ROW_MASK);
> +
> +	pm_runtime_put_sync(csi2dc->dev);

I would really move access to the HW to s_stream time if possible

> +
> +	return ret;
> +}
> +
> +static const struct v4l2_async_notifier_operations csi2dc_async_ops = {
> +	.bound = csi2dc_async_bound,
> +};
> +
> +static void csi2dc_cleanup_notifier(struct csi2dc_device *csi2dc)
> +{
> +	v4l2_async_notifier_unregister(&csi2dc->notifier);
> +	v4l2_async_notifier_cleanup(&csi2dc->notifier);
> +}
> +
> +static int csi2dc_prepare_notifier(struct csi2dc_device *csi2dc,
> +				   struct device_node *input_node)
> +{
> +	int ret = 0;
> +
> +	v4l2_async_notifier_init(&csi2dc->notifier);
> +
> +	csi2dc->asd = v4l2_async_notifier_add_fwnode_remote_subdev

do you need asd in the driver structure ?

> +			(&csi2dc->notifier, of_fwnode_handle(input_node),
> +			struct v4l2_async_subdev);
> +
> +	of_node_put(input_node);
> +
> +	if (IS_ERR(csi2dc->asd)) {
> +		ret = PTR_ERR(csi2dc->asd);
> +		dev_err(csi2dc->dev,
> +			"failed to add async notifier for node %pOF: %d\n",
> +			input_node, ret);
> +		v4l2_async_notifier_cleanup(&csi2dc->notifier);
> +		return ret;
> +	}
> +
> +	csi2dc->notifier.ops = &csi2dc_async_ops;
> +
> +	ret = v4l2_async_subdev_notifier_register(&csi2dc->csi2dc_sd,
> +						  &csi2dc->notifier);
> +
> +	if (ret) {
> +		dev_err(csi2dc->dev, "fail to register async notifier: %d\n",
> +			ret);
> +		v4l2_async_notifier_cleanup(&csi2dc->notifier);
> +	}
> +
> +	return ret;
> +}
> +
> +static int csi2dc_of_parse(struct csi2dc_device *csi2dc,
> +			   struct device_node *of_node)
> +{
> +	struct device_node *input_node, *output_node;
> +	struct v4l2_fwnode_endpoint input_endpoint = { 0 },
> +				    output_endpoint = { 0 };
> +	int ret;
> +
> +	output_endpoint.bus_type = V4L2_MBUS_PARALLEL;
> +
> +	input_node = of_graph_get_next_endpoint(of_node, NULL);
> +
> +	if (!input_node) {
> +		dev_err(csi2dc->dev,
> +			"missing port node at %pOF, input node is mandatory.\n",
> +			of_node);
> +		return -EINVAL;
> +	}
> +
> +	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(input_node),
> +					 &input_endpoint);
> +
> +	if (ret) {
                of_node_put(input_node);

> +		dev_err(csi2dc->dev, "endpoint not defined at %pOF\n", of_node);
> +		return ret;
> +	}
> +
> +	output_node = of_graph_get_next_endpoint(of_node, input_node);
> +
> +	if (output_node)
> +		ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(output_node),
> +						 &output_endpoint);

        of_node_put(output_node);
> +
> +	if (!output_node || ret) {
> +		dev_info(csi2dc->dev,
> +			 "missing output node at %pOF, data pipe available only.\n",
> +			 of_node);
> +	} else {
> +		csi2dc->video_pipe = true;
> +
> +		dev_dbg(csi2dc->dev, "block %pOF %d.%d->%d.%d video pipeline\n",
> +			of_node, input_endpoint.base.port,
> +			input_endpoint.base.id, output_endpoint.base.port,
> +			output_endpoint.base.id);
> +	}
> +
> +	of_node_put(output_node);

Drop this if you put it above

> +	of_node_put(input_node);

Should you put input_node before passing it to the function ?
> +
> +	/* prepare async notifier for subdevice completion */
> +	return csi2dc_prepare_notifier(csi2dc, input_node);
> +}
> +
> +static int csi2dc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct csi2dc_device *csi2dc;
> +	struct resource *res = NULL;
> +	int ret = 0;
> +	u32 ver;
> +
> +	csi2dc = devm_kzalloc(dev, sizeof(*csi2dc), GFP_KERNEL);
> +	if (!csi2dc)
> +		return -ENOMEM;
> +
> +	csi2dc->dev = dev;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> +	csi2dc->base = devm_ioremap_resource(dev, res);

Should devm_platform_ioremap_resource(pdev, 0) be used here ?

> +	if (IS_ERR(csi2dc->base)) {
> +		dev_err(dev, "base address not set\n");
> +		return PTR_ERR(csi2dc->base);
> +	}
> +
> +	csi2dc->pclk = devm_clk_get(dev, "pclk");
> +	if (IS_ERR(csi2dc->pclk)) {
> +		ret = PTR_ERR(csi2dc->pclk);
> +		dev_err(dev, "failed to get pclk: %d\n", ret);
> +		return ret;
> +	}
> +
> +	csi2dc->scck = devm_clk_get(dev, "scck");
> +	if (IS_ERR(csi2dc->scck)) {
> +		ret = PTR_ERR(csi2dc->scck);
> +		dev_err(dev, "failed to get scck: %d\n", ret);
> +		return ret;
> +	}
> +
> +	v4l2_subdev_init(&csi2dc->csi2dc_sd, &csi2dc_subdev_ops);
> +
> +	csi2dc->csi2dc_sd.owner = THIS_MODULE;
> +	csi2dc->csi2dc_sd.dev = dev;
> +	snprintf(csi2dc->csi2dc_sd.name, sizeof(csi2dc->csi2dc_sd.name),
> +		 "csi2dc");
> +
> +	csi2dc->csi2dc_sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	csi2dc->csi2dc_sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> +	v4l2_set_subdevdata(&csi2dc->csi2dc_sd, pdev);

Not used it seems

> +
> +	platform_set_drvdata(pdev, csi2dc);
> +
> +	ret = csi2dc_of_parse(csi2dc, dev->of_node);
> +	if (ret)
> +		goto csi2dc_probe_cleanup_entity;
> +
> +	csi2dc->pads[CSI2DC_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> +	if (csi2dc->video_pipe)
> +		csi2dc->pads[CSI2DC_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
> +
> +	ret = media_entity_pads_init(&csi2dc->csi2dc_sd.entity,
> +				     csi2dc->video_pipe ? CSI2DC_PADS_NUM : 1,
> +				     csi2dc->pads);
> +	if (ret < 0) {
> +		dev_err(dev, "media entity init failed\n");
> +		goto csi2dc_probe_cleanup_entity;

Should you also clean up the notifier in the error path ?

> +	}
> +
> +	/* turn power on to validate capabilities */
> +	ret = csi2dc_power(csi2dc, true);
> +	if (ret < 0)
> +		goto csi2dc_probe_cleanup_entity;
> +
> +	pm_runtime_set_active(dev);
> +	pm_runtime_enable(dev);
> +	ver = csi2dc_readl(csi2dc, CSI2DC_VERSION);
> +	pm_request_idle(dev);
> +
> +	/*
> +	 * we must register the subdev after PM runtime has been requested,
> +	 * otherwise we might bound immediately and request pm_runtime_resume
> +	 * before runtime_enable.
> +	 */
> +	ret = v4l2_async_register_subdev(&csi2dc->csi2dc_sd);
> +	if (ret) {
> +		dev_err(csi2dc->dev, "failed to register the subdevice\n");
> +		goto csi2dc_probe_cleanup_entity;
> +	}
> +
> +	dev_info(dev, "Microchip CSI2DC version %x\n", ver);
> +
> +	return 0;
> +
> +csi2dc_probe_cleanup_entity:
> +	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> +
> +	return ret;
> +}
> +
> +static int csi2dc_remove(struct platform_device *pdev)
> +{
> +	struct csi2dc_device *csi2dc = platform_get_drvdata(pdev);
> +
> +	pm_runtime_disable(&pdev->dev);
> +
> +	v4l2_async_unregister_subdev(&csi2dc->csi2dc_sd);
> +	csi2dc_cleanup_notifier(csi2dc);
> +	media_entity_cleanup(&csi2dc->csi2dc_sd.entity);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused csi2dc_runtime_suspend(struct device *dev)
> +{
> +	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> +
> +	return csi2dc_power(csi2dc, false);
> +}
> +
> +static int __maybe_unused csi2dc_runtime_resume(struct device *dev)
> +{
> +	struct csi2dc_device *csi2dc = dev_get_drvdata(dev);
> +
> +	return csi2dc_power(csi2dc, true);
> +}
> +
> +static const struct dev_pm_ops csi2dc_dev_pm_ops = {
> +	SET_RUNTIME_PM_OPS(csi2dc_runtime_suspend, csi2dc_runtime_resume, NULL)
> +};
> +
> +static const struct of_device_id csi2dc_of_match[] = {
> +	{ .compatible = "microchip,sama7g5-csi2dc" },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(of, csi2dc_of_match);
> +
> +static struct platform_driver csi2dc_driver = {
> +	.probe	= csi2dc_probe,
> +	.remove = csi2dc_remove,
> +	.driver = {
> +		.name =			"microchip-csi2dc",
> +		.pm =			&csi2dc_dev_pm_ops,
> +		.of_match_table =	of_match_ptr(csi2dc_of_match),
> +	},
> +};
> +
> +module_platform_driver(csi2dc_driver);
> +
> +MODULE_AUTHOR("Eugen Hristev <eugen.hristev@...rochip.com>");
> +MODULE_DESCRIPTION("Microchip CSI2 Demux Controller driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.25.1
>

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