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Date: Fri, 31 May 2024 13:56:35 +0000
From: Sakari Ailus <sakari.ailus@iki.fi>
To: Julien Massot <julien.massot@collabora.com>
Cc: linux-media@vger.kernel.org, devicetree@vger.kernel.org,
	kernel@collabora.com, linux-kernel@vger.kernel.org,
	mchehab@kernel.org, robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org
Subject: Re: [PATCH v7 3/5] media: i2c: add MAX96717 driver
Message-ID: <ZlnXE3sDcnrP31XM@valkosipuli.retiisi.eu>
References: <20240430131931.166012-1-julien.massot@collabora.com>
 <20240430131931.166012-4-julien.massot@collabora.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240430131931.166012-4-julien.massot@collabora.com>

Hi Julien,

A few fairly minor comments below... they probably apply to the other
driver, too.

On Tue, Apr 30, 2024 at 03:19:29PM +0200, Julien Massot wrote:
> This driver handles the MAX96717 serializer in tunnel mode.
> All incoming CSI traffic will be tunneled through the GMSL2
> link.
> 
> The MAX96717 driver can handle MAX96717 and MAX96717F variants
> with the same "maxim,max96717f" compatible.
> 
> Signed-off-by: Julien Massot <julien.massot@collabora.com>
> ---
> Change since v6:
>  - Kconfig select MEDIA_CONTROLLER, V4L2_FWNODE and VIDEO_V4L2_SUBDEV_API
>  - rename 'REG3' register to 'MAX96717_REG3'
>  - Initialized 'ret' variable in 'max96717_gpiochip_probe'
>  - remove max96714_v4l2_notifier_unregister and call the function directly
>  - Do not store private pointer with i2c_set_clientdata since the v4l2-i2c
>    uses it to store the subdev pointer
>  - use dev_err_probe at gpio chip initialization
> 
> Change since v5:
>  - set the driver compatible back to MAX96717F that can be used as a fallback for MAX96717
> 
> Change since v4:
>  - make the driver compatible with MAX96717 instead of MAX96717F
>  - Add the device id for the MAX96717
>  - remove hw_data structure for now, it can be usefull later for handling different serializers e.g max9295
> 
> Change since v3:
>  - Maintainers: align to the new binding path
>  - Kconfig: better describe the symbol
>  - store the v4l2_mbus_config_mipi_csi2 structure instead of the full endpoint in the driver private structure
>  - use MAX96717_PAD_SINK/SOURCE instead of 0/1 for pad intialization
>  - Removed incorrect call to fwnode_handle_put(priv->sd.fwnode)
>  - Use unsigned int instead of u8
>  - Allocate clk name out of the clk struct initialization
>  - fixed multiline comment
>  - Removed one unnecessary goto at the end of the probe function
> 
> Change since v2:
>  - Use CCI helpers instead of recoding register access
>  - add missing bitfield header
> ---
>  MAINTAINERS                  |   7 +
>  drivers/media/i2c/Kconfig    |  17 +
>  drivers/media/i2c/Makefile   |   1 +
>  drivers/media/i2c/max96717.c | 928 +++++++++++++++++++++++++++++++++++
>  4 files changed, 953 insertions(+)
>  create mode 100644 drivers/media/i2c/max96717.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index eea74166a2d9..cfaa904ace59 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -13426,6 +13426,13 @@ S:	Maintained
>  F:	Documentation/devicetree/bindings/media/i2c/maxim,max96712.yaml
>  F:	drivers/staging/media/max96712/max96712.c
>  
> +MAX96717 GMSL2 SERIALIZER DRIVER
> +M:	Julien Massot <julien.massot@collabora.com>
> +L:	linux-media@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/media/i2c/maxim,max96717.yaml
> +F:	drivers/media/i2c/max96717.c
> +
>  MAX9860 MONO AUDIO VOICE CODEC DRIVER
>  M:	Peter Rosin <peda@axentia.se>
>  L:	alsa-devel@alsa-project.org (moderated for non-subscribers)
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index c6d3ee472d81..9918195e09ba 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -1575,6 +1575,23 @@ config VIDEO_DS90UB960
>  	  Device driver for the Texas Instruments DS90UB960
>  	  FPD-Link III Deserializer and DS90UB9702 FPD-Link IV Deserializer.
>  
> +config VIDEO_MAX96717
> +	tristate "Maxim MAX96717 GMSL2 Serializer support"
> +	depends on OF && I2C && VIDEO_DEV && COMMON_CLK
> +	select I2C_MUX
> +	select MEDIA_CONTROLLER
> +	select GPIOLIB
> +	select V4L2_CCI_I2C
> +	select V4L2_FWNODE
> +	select VIDEO_V4L2_SUBDEV_API
> +	help
> +	  Device driver for the Maxim MAX96717 GMSL2 Serializer.
> +	  MAX96717 serializers convert video on a MIPI CSI-2
> +	  input to a GMSL2 output.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called max96717.
> +
>  endmenu
>  
>  endif # VIDEO_DEV
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index dfbe6448b549..9e007116f929 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -64,6 +64,7 @@ obj-$(CONFIG_VIDEO_LM3646) += lm3646.o
>  obj-$(CONFIG_VIDEO_M52790) += m52790.o
>  obj-$(CONFIG_VIDEO_MAX9271_LIB) += max9271.o
>  obj-$(CONFIG_VIDEO_MAX9286) += max9286.o
> +obj-$(CONFIG_VIDEO_MAX96717) += max96717.o
>  obj-$(CONFIG_VIDEO_ML86V7667) += ml86v7667.o
>  obj-$(CONFIG_VIDEO_MSP3400) += msp3400.o
>  obj-$(CONFIG_VIDEO_MT9M001) += mt9m001.o
> diff --git a/drivers/media/i2c/max96717.c b/drivers/media/i2c/max96717.c
> new file mode 100644
> index 000000000000..1ea76f922bdb
> --- /dev/null
> +++ b/drivers/media/i2c/max96717.c
> @@ -0,0 +1,928 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Maxim GMSL2 Serializer Driver
> + *
> + * Copyright (C) 2024 Collabora Ltd.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/delay.h>
> +#include <linux/fwnode.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/i2c-mux.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
> +
> +#include <media/v4l2-cci.h>
> +#include <media/v4l2-fwnode.h>
> +#include <media/v4l2-subdev.h>
> +
> +#define MAX96717_DEVICE_ID  0xbf
> +#define MAX96717F_DEVICE_ID 0xc8
> +#define MAX96717_PORTS      2
> +#define MAX96717_PAD_SINK   0
> +#define MAX96717_PAD_SOURCE 1
> +
> +#define MAX96717_DEFAULT_CLKOUT_RATE	24000000UL
> +
> +/* DEV */
> +#define MAX96717_REG3    CCI_REG8(0x3)
> +#define MAX96717_RCLKSEL GENMASK(1, 0)
> +#define RCLKSEL_REF_PLL  CCI_REG8(0x3)
> +#define MAX96717_REG6    CCI_REG8(0x6)
> +#define RCLKEN           BIT(5)
> +#define MAX96717_DEV_ID  CCI_REG8(0xd)
> +#define MAX96717_DEV_REV CCI_REG8(0xe)
> +#define MAX96717_DEV_REV_MASK GENMASK(3, 0)
> +
> +/* VID_TX Z */
> +#define MAX96717_VIDEO_TX2 CCI_REG8(0x112)
> +#define MAX96717_VIDEO_PCLKDET BIT(7)
> +
> +/* GPIO */
> +#define MAX96717_NUM_GPIO         11
> +#define MAX96717_GPIO_REG_A(gpio) CCI_REG8(0x2be + (gpio) * 3)
> +#define MAX96717_GPIO_OUT         BIT(4)
> +#define MAX96717_GPIO_IN          BIT(3)
> +#define MAX96717_GPIO_RX_EN       BIT(2)
> +#define MAX96717_GPIO_TX_EN       BIT(1)
> +#define MAX96717_GPIO_OUT_DIS     BIT(0)
> +
> +/* FRONTTOP */
> +/* MAX96717 only have CSI port 'B' */
> +#define MAX96717_FRONTOP0     CCI_REG8(0x308)
> +#define MAX96717_START_PORT_B BIT(5)
> +
> +/* MIPI_RX */
> +#define MAX96717_MIPI_RX1       CCI_REG8(0x331)
> +#define MAX96717_MIPI_LANES_CNT GENMASK(5, 4)
> +#define MAX96717_MIPI_RX2       CCI_REG8(0x332) /* phy1 Lanes map */
> +#define MAX96717_PHY2_LANES_MAP GENMASK(7, 4)
> +#define MAX96717_MIPI_RX3       CCI_REG8(0x333) /* phy2 Lanes map */
> +#define MAX96717_PHY1_LANES_MAP GENMASK(3, 0)
> +#define MAX96717_MIPI_RX4       CCI_REG8(0x334) /* phy1 lane polarities */
> +#define MAX96717_PHY1_LANES_POL GENMASK(6, 4)
> +#define MAX96717_MIPI_RX5       CCI_REG8(0x335) /* phy2 lane polarities */
> +#define MAX96717_PHY2_LANES_POL GENMASK(2, 0)
> +
> +/* MIPI_RX_EXT */
> +#define MAX96717_MIPI_RX_EXT11 CCI_REG8(0x383)
> +#define MAX96717_TUN_MODE      BIT(7)
> +
> +/* REF_VTG */
> +#define REF_VTG0                CCI_REG8(0x3f0)
> +#define REFGEN_PREDEF_EN        BIT(6)
> +#define REFGEN_PREDEF_FREQ_MASK GENMASK(5, 4)
> +#define REFGEN_PREDEF_FREQ_ALT  BIT(3)
> +#define REFGEN_RST              BIT(1)
> +#define REFGEN_EN               BIT(0)
> +
> +/* MISC */
> +#define PIO_SLEW_1 CCI_REG8(0x570)
> +
> +struct max96717_priv {
> +	struct i2c_client		  *client;
> +	struct regmap			  *regmap;
> +	struct i2c_mux_core		  *mux;
> +	struct v4l2_mbus_config_mipi_csi2 mipi_csi2;
> +	struct v4l2_subdev                sd;
> +	struct media_pad                  pads[MAX96717_PORTS];
> +	struct v4l2_async_notifier        notifier;
> +	struct v4l2_subdev                *source_sd;
> +	u16                               source_sd_pad;
> +	u64			          enabled_source_streams;
> +	u8                                pll_predef_index;
> +	struct clk_hw                     clk_hw;
> +	struct gpio_chip                  gpio_chip;
> +};
> +
> +static inline struct max96717_priv *sd_to_max96717(struct v4l2_subdev *sd)
> +{
> +	return container_of(sd, struct max96717_priv, sd);
> +}
> +
> +static inline struct max96717_priv *clk_hw_to_max96717(struct clk_hw *hw)
> +{
> +	return container_of(hw, struct max96717_priv, clk_hw);
> +}
> +
> +static int max96717_i2c_mux_select(struct i2c_mux_core *mux, u32 chan)
> +{
> +	return 0;
> +}
> +
> +static int max96717_i2c_mux_init(struct max96717_priv *priv)
> +{
> +	priv->mux = i2c_mux_alloc(priv->client->adapter, &priv->client->dev,
> +				  1, 0, I2C_MUX_LOCKED | I2C_MUX_GATE,
> +				  max96717_i2c_mux_select, NULL);
> +	if (!priv->mux)
> +		return -ENOMEM;
> +
> +	return i2c_mux_add_adapter(priv->mux, 0, 0, 0);
> +}
> +
> +static inline int max96717_start_csi(struct max96717_priv *priv, bool start)
> +{
> +	return cci_update_bits(priv->regmap, MAX96717_FRONTOP0,
> +			       MAX96717_START_PORT_B,
> +			       start ? MAX96717_START_PORT_B : 0, NULL);
> +}
> +
> +static int max96717_gpiochip_get(struct gpio_chip *gpiochip,
> +				 unsigned int offset)
> +{
> +	struct max96717_priv *priv = gpiochip_get_data(gpiochip);
> +	u64 val;
> +	int ret;
> +
> +	ret = cci_read(priv->regmap, MAX96717_GPIO_REG_A(offset),
> +		       &val, NULL);
> +	if (ret)
> +		return ret;
> +
> +	if (val & MAX96717_GPIO_OUT_DIS)
> +		return !!(val & MAX96717_GPIO_IN);
> +	else
> +		return !!(val & MAX96717_GPIO_OUT);
> +}
> +
> +static void max96717_gpiochip_set(struct gpio_chip *gpiochip,
> +				  unsigned int offset, int value)
> +{
> +	struct max96717_priv *priv = gpiochip_get_data(gpiochip);
> +
> +	cci_update_bits(priv->regmap, MAX96717_GPIO_REG_A(offset),
> +			MAX96717_GPIO_OUT, MAX96717_GPIO_OUT, NULL);
> +}
> +
> +static int max96717_gpio_get_direction(struct gpio_chip *gpiochip,
> +				       unsigned int offset)
> +{
> +	struct max96717_priv *priv = gpiochip_get_data(gpiochip);
> +	u64 val;
> +	int ret;
> +
> +	ret = cci_read(priv->regmap, MAX96717_GPIO_REG_A(offset), &val, NULL);
> +	if (ret < 0)
> +		return ret;
> +
> +	return !!(val & MAX96717_GPIO_OUT_DIS);
> +}
> +
> +static int max96717_gpio_direction_out(struct gpio_chip *gpiochip,
> +				       unsigned int offset, int value)
> +{
> +	struct max96717_priv *priv = gpiochip_get_data(gpiochip);
> +
> +	return cci_update_bits(priv->regmap, MAX96717_GPIO_REG_A(offset),
> +			       MAX96717_GPIO_OUT_DIS | MAX96717_GPIO_OUT,
> +			       value ? MAX96717_GPIO_OUT : 0, NULL);
> +}
> +
> +static int max96717_gpio_direction_in(struct gpio_chip *gpiochip,
> +				      unsigned int offset)
> +{
> +	struct max96717_priv *priv = gpiochip_get_data(gpiochip);
> +
> +	return cci_update_bits(priv->regmap, MAX96717_GPIO_REG_A(offset),
> +			       MAX96717_GPIO_OUT_DIS, MAX96717_GPIO_OUT_DIS,
> +			       NULL);
> +}
> +
> +static int max96717_gpiochip_probe(struct max96717_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct gpio_chip *gc = &priv->gpio_chip;
> +	int i, ret = 0;
> +
> +	gc->label = dev_name(dev);
> +	gc->parent = dev;
> +	gc->owner = THIS_MODULE;
> +	gc->ngpio = MAX96717_NUM_GPIO;
> +	gc->base = -1;
> +	gc->can_sleep = true;
> +	gc->get_direction = max96717_gpio_get_direction;
> +	gc->direction_input = max96717_gpio_direction_in;
> +	gc->direction_output = max96717_gpio_direction_out;
> +	gc->set = max96717_gpiochip_set;
> +	gc->get = max96717_gpiochip_get;
> +	gc->of_gpio_n_cells = 2;
> +
> +	/* Disable GPIO forwarding */
> +	for (i = 0; i < gc->ngpio; i++)
> +		cci_update_bits(priv->regmap, MAX96717_GPIO_REG_A(i),
> +				MAX96717_GPIO_RX_EN | MAX96717_GPIO_TX_EN,
> +				0, &ret);
> +
> +	if (ret)
> +		return ret;
> +
> +	ret = devm_gpiochip_add_data(dev, gc, priv);
> +	if (ret) {
> +		dev_err(dev, "Unable to create gpio_chip\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int _max96717_set_routing(struct v4l2_subdev *sd,
> +				 struct v4l2_subdev_state *state,
> +				 struct v4l2_subdev_krouting *routing)
> +{
> +	static const struct v4l2_mbus_framefmt format = {
> +		.width = 1280,
> +		.height = 1080,
> +		.code = MEDIA_BUS_FMT_Y8_1X8,
> +		.field = V4L2_FIELD_NONE,
> +	};
> +	int ret;
> +
> +	ret = v4l2_subdev_routing_validate(sd, routing,
> +					   V4L2_SUBDEV_ROUTING_ONLY_1_TO_1);
> +	if (ret)
> +		return ret;
> +
> +	ret = v4l2_subdev_set_routing_with_fmt(sd, state, routing, &format);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int max96717_set_routing(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *state,
> +				enum v4l2_subdev_format_whence which,
> +				struct v4l2_subdev_krouting *routing)
> +{
> +	struct max96717_priv *priv = sd_to_max96717(sd);
> +
> +	if (which == V4L2_SUBDEV_FORMAT_ACTIVE && priv->enabled_source_streams)
> +		return -EBUSY;
> +
> +	return _max96717_set_routing(sd, state, routing);
> +}
> +
> +static int max96717_set_fmt(struct v4l2_subdev *sd,
> +			    struct v4l2_subdev_state *state,
> +			    struct v4l2_subdev_format *format)
> +{
> +	struct max96717_priv *priv = sd_to_max96717(sd);
> +	struct v4l2_mbus_framefmt *fmt;
> +	u64 stream_source_mask;
> +
> +	if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE &&
> +	    priv->enabled_source_streams)
> +		return -EBUSY;
> +
> +	/* No transcoding, source and sink formats must match. */
> +	if (format->pad == MAX96717_PAD_SOURCE)
> +		return v4l2_subdev_get_fmt(sd, state, format);
> +
> +	/* Set sink format */
> +	fmt = v4l2_subdev_state_get_format(state, format->pad, format->stream);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	*fmt = format->format;
> +
> +	/* Propagate to source format */
> +	fmt = v4l2_subdev_state_get_opposite_stream_format(state, format->pad,
> +							   format->stream);
> +	if (!fmt)
> +		return -EINVAL;
> +	*fmt = format->format;
> +
> +	stream_source_mask = BIT(format->stream);
> +
> +	return v4l2_subdev_state_xlate_streams(state, MAX96717_PAD_SOURCE,
> +					       MAX96717_PAD_SINK,
> +					       &stream_source_mask);
> +}
> +
> +static int max96717_init_state(struct v4l2_subdev *sd,
> +			       struct v4l2_subdev_state *state)
> +{
> +	struct v4l2_subdev_route routes[] = {
> +		{
> +			.sink_pad = MAX96717_PAD_SINK,
> +			.sink_stream = 0,
> +			.source_pad = MAX96717_PAD_SOURCE,
> +			.source_stream = 0,
> +			.flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE,
> +		},
> +	};
> +	struct v4l2_subdev_krouting routing = {
> +		.num_routes = ARRAY_SIZE(routes),
> +		.routes = routes,
> +	};
> +
> +	return _max96717_set_routing(sd, state, &routing);
> +}
> +
> +static bool max96717_pipe_pclkdet(struct max96717_priv *priv)
> +{
> +	u64 val = 0;
> +
> +	cci_read(priv->regmap, MAX96717_VIDEO_TX2, &val, NULL);
> +
> +	return val & MAX96717_VIDEO_PCLKDET;
> +}
> +
> +static int max96717_log_status(struct v4l2_subdev *sd)
> +{
> +	struct max96717_priv *priv = sd_to_max96717(sd);
> +	struct device *dev = &priv->client->dev;
> +
> +	dev_info(dev, "Serializer: max96717\n");
> +	dev_info(dev, "Pipe: pclkdet:%d\n", max96717_pipe_pclkdet(priv));
> +
> +	return 0;
> +}
> +
> +static int max96717_enable_streams(struct v4l2_subdev *sd,
> +				   struct v4l2_subdev_state *state, u32 pad,
> +				   u64 streams_mask)
> +{
> +	struct max96717_priv *priv = sd_to_max96717(sd);
> +	struct device *dev = &priv->client->dev;
> +	u64 sink_streams;
> +	int ret;
> +
> +	sink_streams = v4l2_subdev_state_xlate_streams(state,
> +						       MAX96717_PAD_SOURCE,
> +						       MAX96717_PAD_SINK,
> +						       &streams_mask);
> +
> +	if (!priv->enabled_source_streams)
> +		max96717_start_csi(priv, true);
> +
> +	ret = v4l2_subdev_enable_streams(priv->source_sd, priv->source_sd_pad,
> +					 sink_streams);
> +	if (ret) {
> +		dev_err(dev, "Fail to start streams:%llu on remote subdev\n",
> +			sink_streams);

Doesn't v4l2_subdev_enable_streams() print this?

> +		goto stop_csi;
> +	}
> +
> +	priv->enabled_source_streams |= streams_mask;
> +
> +	return 0;
> +
> +stop_csi:
> +	if (!priv->enabled_source_streams)
> +		max96717_start_csi(priv, false);

A newline would be nice here.

> +	return ret;
> +}
> +
> +static int max96717_disable_streams(struct v4l2_subdev *sd,
> +				    struct v4l2_subdev_state *state, u32 pad,
> +				    u64 streams_mask)
> +{
> +	struct max96717_priv *priv = sd_to_max96717(sd);
> +	u64 sink_streams;
> +	int ret;
> +
> +	sink_streams = v4l2_subdev_state_xlate_streams(state,
> +						       MAX96717_PAD_SOURCE,
> +						       MAX96717_PAD_SINK,
> +						       &streams_mask);
> +
> +	ret = v4l2_subdev_disable_streams(priv->source_sd, priv->source_sd_pad,
> +					  sink_streams);
> +	if (ret)
> +		return ret;
> +
> +	priv->enabled_source_streams &= ~streams_mask;
> +
> +	if (!priv->enabled_source_streams)
> +		max96717_start_csi(priv, false);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_pad_ops max96717_pad_ops = {
> +	.enable_streams = max96717_enable_streams,
> +	.disable_streams = max96717_disable_streams,
> +	.set_routing = max96717_set_routing,
> +	.get_fmt = v4l2_subdev_get_fmt,
> +	.set_fmt = max96717_set_fmt,
> +};
> +
> +static const struct v4l2_subdev_core_ops max96717_subdev_core_ops = {
> +	.log_status = max96717_log_status,
> +};
> +
> +static const struct v4l2_subdev_internal_ops max96717_internal_ops = {
> +	.init_state = max96717_init_state,
> +};
> +
> +static const struct v4l2_subdev_ops max96717_subdev_ops = {
> +	.core = &max96717_subdev_core_ops,
> +	.pad = &max96717_pad_ops,
> +};
> +
> +static const struct media_entity_operations max96717_entity_ops = {
> +	.link_validate = v4l2_subdev_link_validate,
> +};
> +
> +static int max96717_notify_bound(struct v4l2_async_notifier *notifier,
> +				 struct v4l2_subdev *source_subdev,
> +				 struct v4l2_async_connection *asd)
> +{
> +	struct max96717_priv *priv = sd_to_max96717(notifier->sd);
> +	struct device *dev = &priv->client->dev;
> +	int ret;
> +
> +	ret = media_entity_get_fwnode_pad(&source_subdev->entity,
> +					  source_subdev->fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to find pad for %s\n",
> +			source_subdev->name);
> +		return ret;
> +	}
> +
> +	priv->source_sd = source_subdev;
> +	priv->source_sd_pad = ret;
> +
> +	ret = media_create_pad_link(&source_subdev->entity, priv->source_sd_pad,
> +				    &priv->sd.entity, 0,
> +				    MEDIA_LNK_FL_ENABLED |
> +				    MEDIA_LNK_FL_IMMUTABLE);
> +	if (ret) {
> +		dev_err(dev, "Unable to link %s:%u -> %s:0\n",
> +			source_subdev->name, priv->source_sd_pad,
> +			priv->sd.name);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_async_notifier_operations max96717_notify_ops = {
> +	.bound = max96717_notify_bound,
> +};
> +
> +static int max96717_v4l2_notifier_register(struct max96717_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct v4l2_async_connection *asd;
> +	struct fwnode_handle *ep_fwnode;
> +	int ret;
> +
> +	ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
> +						    MAX96717_PAD_SINK, 0, 0);
> +	if (!ep_fwnode) {
> +		dev_err(dev, "No graph endpoint\n");
> +		return -ENODEV;
> +	}
> +
> +	v4l2_async_subdev_nf_init(&priv->notifier, &priv->sd);
> +
> +	asd = v4l2_async_nf_add_fwnode_remote(&priv->notifier, ep_fwnode,
> +					      struct v4l2_async_connection);
> +
> +	fwnode_handle_put(ep_fwnode);
> +
> +	if (IS_ERR(asd)) {
> +		dev_err(dev, "Failed to add subdev: %ld", PTR_ERR(asd));
> +		v4l2_async_nf_cleanup(&priv->notifier);
> +		return PTR_ERR(asd);
> +	}
> +
> +	priv->notifier.ops = &max96717_notify_ops;
> +
> +	ret = v4l2_async_nf_register(&priv->notifier);
> +	if (ret) {
> +		dev_err(dev, "Failed to register subdev_notifier");
> +		v4l2_async_nf_cleanup(&priv->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int max96717_subdev_init(struct max96717_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	int ret;
> +
> +	v4l2_i2c_subdev_init(&priv->sd, priv->client, &max96717_subdev_ops);
> +	priv->sd.internal_ops = &max96717_internal_ops;
> +
> +	priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_STREAMS;
> +	priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> +	priv->sd.entity.ops = &max96717_entity_ops;
> +
> +	priv->pads[MAX96717_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
> +	priv->pads[MAX96717_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE;
> +
> +	ret = media_entity_pads_init(&priv->sd.entity, 2, priv->pads);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to init pads\n");
> +
> +	ret = v4l2_subdev_init_finalize(&priv->sd);
> +	if (ret) {
> +		dev_err_probe(dev, ret,
> +			      "v4l2 subdev init finalized failed\n");
> +		goto err_entity_cleanup;
> +	}
> +	ret = max96717_v4l2_notifier_register(priv);
> +	if (ret) {
> +		dev_err_probe(dev, ret,
> +			      "v4l2 subdev notifier register failed\n");
> +		goto err_free_state;
> +	}
> +
> +	ret = v4l2_async_register_subdev(&priv->sd);
> +	if (ret) {
> +		dev_err_probe(dev, ret, "v4l2_async_register_subdev error\n");
> +		goto err_unreg_notif;
> +	}
> +
> +	return 0;
> +
> +err_unreg_notif:
> +	v4l2_async_nf_unregister(&priv->notifier);
> +	v4l2_async_nf_cleanup(&priv->notifier);
> +err_free_state:
> +	v4l2_subdev_cleanup(&priv->sd);
> +err_entity_cleanup:
> +	media_entity_cleanup(&priv->sd.entity);
> +
> +	return ret;
> +}
> +
> +static void max96717_subdev_uninit(struct max96717_priv *priv)
> +{
> +	v4l2_async_unregister_subdev(&priv->sd);
> +	v4l2_async_nf_unregister(&priv->notifier);
> +	v4l2_async_nf_cleanup(&priv->notifier);
> +	v4l2_subdev_cleanup(&priv->sd);
> +	media_entity_cleanup(&priv->sd.entity);
> +}
> +
> +struct max96717_pll_predef_freq {
> +	unsigned long freq;
> +	bool is_alt;
> +	u8 val;
> +};
> +
> +static const struct max96717_pll_predef_freq max96717_predef_freqs[] = {
> +	{ 13500000, true,  0 }, { 19200000, false, 0 },
> +	{ 24000000, true,  1 }, { 27000000, false, 1 },
> +	{ 37125000, false, 2 }, { 74250000, false, 3 },
> +};
> +
> +static unsigned long
> +max96717_clk_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
> +{
> +	struct max96717_priv *priv = clk_hw_to_max96717(hw);
> +
> +	return max96717_predef_freqs[priv->pll_predef_index].freq;
> +}
> +
> +static unsigned int max96717_clk_find_best_index(struct max96717_priv *priv,
> +						 unsigned long rate)
> +{
> +	unsigned int i, idx;
> +	unsigned long diff_new, diff_old;
> +
> +	diff_old = U32_MAX;
> +	idx = 0;

Please initialise in declaration (or loop below).

> +
> +	for (i = 0; i < ARRAY_SIZE(max96717_predef_freqs); i++) {
> +		diff_new = abs(rate - max96717_predef_freqs[i].freq);
> +		if (diff_new < diff_old) {
> +			diff_old = diff_new;
> +			idx = i;
> +		}
> +	}
> +
> +	return idx;
> +}
> +
> +static long max96717_clk_round_rate(struct clk_hw *hw, unsigned long rate,
> +				    unsigned long *parent_rate)
> +{
> +	struct max96717_priv *priv = clk_hw_to_max96717(hw);
> +	struct device *dev = &priv->client->dev;
> +	unsigned int idx;
> +
> +	idx = max96717_clk_find_best_index(priv, rate);
> +
> +	if (rate != max96717_predef_freqs[idx].freq) {
> +		dev_warn(dev, "Request CLK freq:%lu, found CLK freq:%lu\n",
> +			 rate, max96717_predef_freqs[idx].freq);
> +	}
> +
> +	return max96717_predef_freqs[idx].freq;
> +}
> +
> +static int max96717_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> +				 unsigned long parent_rate)
> +{
> +	struct max96717_priv *priv = clk_hw_to_max96717(hw);
> +	unsigned int val, idx;
> +	int ret = 0;
> +
> +	idx = max96717_clk_find_best_index(priv, rate);
> +
> +	val = FIELD_PREP(REFGEN_PREDEF_FREQ_MASK,
> +			 max96717_predef_freqs[idx].val);
> +
> +	if (max96717_predef_freqs[idx].is_alt)
> +		val |= REFGEN_PREDEF_FREQ_ALT;
> +
> +	val |= REFGEN_RST | REFGEN_PREDEF_EN;
> +
> +	cci_write(priv->regmap, REF_VTG0, val, &ret);
> +	cci_update_bits(priv->regmap, REF_VTG0, REFGEN_RST | REFGEN_EN,
> +			REFGEN_EN, &ret);
> +	if (ret)
> +		return ret;
> +
> +	priv->pll_predef_index = idx;
> +
> +	return 0;
> +}
> +
> +static int max96717_clk_prepare(struct clk_hw *hw)
> +{
> +	struct max96717_priv *priv = clk_hw_to_max96717(hw);
> +
> +	return cci_update_bits(priv->regmap, MAX96717_REG6, RCLKEN,
> +			       RCLKEN, NULL);
> +}
> +
> +static void max96717_clk_unprepare(struct clk_hw *hw)
> +{
> +	struct max96717_priv *priv = clk_hw_to_max96717(hw);
> +
> +	cci_update_bits(priv->regmap, MAX96717_REG6, RCLKEN, 0, NULL);
> +}
> +
> +static const struct clk_ops max96717_clk_ops = {
> +	.prepare     = max96717_clk_prepare,
> +	.unprepare   = max96717_clk_unprepare,
> +	.set_rate    = max96717_clk_set_rate,
> +	.recalc_rate = max96717_clk_recalc_rate,
> +	.round_rate  = max96717_clk_round_rate,
> +};
> +
> +static int max96717_register_clkout(struct max96717_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct clk_init_data init = { .ops = &max96717_clk_ops };
> +	int ret;
> +
> +	init.name = kasprintf(GFP_KERNEL, "max96717.%s.clk_out",
> +			      dev_name(dev));

Fits on the previous line.

> +	if (!init.name)
> +		return -ENOMEM;
> +
> +	/* RCLKSEL Reference PLL output */
> +	ret = cci_update_bits(priv->regmap, MAX96717_REG3, MAX96717_RCLKSEL,
> +			      MAX96717_RCLKSEL, NULL);
> +	/* MFP4 fastest slew rate */
> +	cci_update_bits(priv->regmap, PIO_SLEW_1, BIT(5) | BIT(4), 0, &ret);
> +	if (ret)
> +		goto free_init_name;
> +
> +	priv->clk_hw.init = &init;
> +
> +	/* Initialize to 24 MHz */
> +	ret = max96717_clk_set_rate(&priv->clk_hw,
> +				    MAX96717_DEFAULT_CLKOUT_RATE, 0);
> +	if (ret < 0)
> +		goto free_init_name;
> +
> +	ret = devm_clk_hw_register(dev, &priv->clk_hw);
> +	kfree(init.name);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Cannot register clock HW\n");
> +
> +	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
> +					  &priv->clk_hw);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Cannot add OF clock provider\n");
> +
> +	return 0;
> +
> +free_init_name:
> +	kfree(init.name);
> +	return ret;
> +}
> +
> +static int max96717_init_csi_lanes(struct max96717_priv *priv)
> +{
> +	struct v4l2_mbus_config_mipi_csi2 *mipi = &priv->mipi_csi2;
> +	unsigned long lanes_used = 0;
> +	unsigned int nlanes, lane, val = 0;
> +	int ret;
> +
> +	nlanes = mipi->num_data_lanes;
> +
> +	ret = cci_update_bits(priv->regmap, MAX96717_MIPI_RX1,
> +			      MAX96717_MIPI_LANES_CNT,
> +			      FIELD_PREP(MAX96717_MIPI_LANES_CNT,
> +					 nlanes - 1), NULL);
> +
> +	/* lanes polarity */
> +	for (lane = 0; lane < nlanes + 1; lane++) {
> +		if (!mipi->lane_polarities[lane])
> +			continue;
> +		/* Clock lane */
> +		if (lane == 0)
> +			val |= BIT(2);
> +		else if (lane < 3)
> +			val |= BIT(lane - 1);
> +		else
> +			val |= BIT(lane);
> +	}
> +
> +	cci_update_bits(priv->regmap, MAX96717_MIPI_RX5,
> +			MAX96717_PHY2_LANES_POL,
> +			FIELD_PREP(MAX96717_PHY2_LANES_POL, val), &ret);
> +
> +	cci_update_bits(priv->regmap, MAX96717_MIPI_RX4,
> +			MAX96717_PHY1_LANES_POL,
> +			FIELD_PREP(MAX96717_PHY1_LANES_POL,
> +				   val >> 3), &ret);
> +	/* lanes mapping */
> +	for (lane = 0, val = 0; lane < nlanes; lane++) {
> +		val |= (mipi->data_lanes[lane] - 1) << (lane * 2);
> +		lanes_used |= BIT(mipi->data_lanes[lane] - 1);
> +	}
> +
> +	/*
> +	 * Unused lanes need to be mapped as well to not have
> +	 * the same lanes mapped twice.
> +	 */
> +	for (; lane < 4; lane++) {
> +		unsigned int idx = find_first_zero_bit(&lanes_used, 4);

It'd be nice to use a macro here instead of "4". Same elsewhere.

> +
> +		val |= idx << (lane * 2);
> +		lanes_used |= BIT(idx);
> +	}
> +
> +	cci_update_bits(priv->regmap, MAX96717_MIPI_RX3,
> +			MAX96717_PHY1_LANES_MAP,
> +			FIELD_PREP(MAX96717_PHY1_LANES_MAP, val), &ret);
> +
> +	return cci_update_bits(priv->regmap, MAX96717_MIPI_RX2,
> +			       MAX96717_PHY2_LANES_MAP,
> +			       FIELD_PREP(MAX96717_PHY2_LANES_MAP, val >> 4),
> +			       &ret);
> +}
> +
> +static int max96717_hw_init(struct max96717_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	u64 dev_id, val;
> +	int ret;
> +
> +	ret = cci_read(priv->regmap, MAX96717_DEV_ID, &dev_id, NULL);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Fail to read the device id\n");
> +
> +	if (dev_id != MAX96717_DEVICE_ID && dev_id != MAX96717F_DEVICE_ID)
> +		return dev_err_probe(dev, -EOPNOTSUPP,
> +				     "Unsupported device id got %x\n", (u8)dev_id);
> +
> +	ret = cci_read(priv->regmap, MAX96717_DEV_REV, &val, NULL);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Fail to read device revision");
> +
> +	dev_dbg(dev, "Found %x (rev %lx)\n", (u8)dev_id,
> +		(u8)val & MAX96717_DEV_REV_MASK);
> +
> +	ret = cci_read(priv->regmap, MAX96717_MIPI_RX_EXT11, &val, NULL);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Fail to read mipi rx extension");
> +
> +	if (!(val & MAX96717_TUN_MODE))
> +		return dev_err_probe(dev, -EOPNOTSUPP,
> +				     "Only supporting tunnel mode");
> +
> +	return max96717_init_csi_lanes(priv);
> +}
> +
> +static int max96717_parse_dt(struct max96717_priv *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct v4l2_fwnode_endpoint vep = {
> +		.bus_type = V4L2_MBUS_CSI2_DPHY
> +	};

Fits on a single line.

> +	struct fwnode_handle *ep_fwnode;
> +	unsigned char num_data_lanes;
> +	int ret;
> +
> +	ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
> +						    MAX96717_PAD_SINK, 0, 0);
> +	if (!ep_fwnode)
> +		return dev_err_probe(dev, -ENOENT, "no endpoint found\n");
> +
> +	ret = v4l2_fwnode_endpoint_parse(ep_fwnode, &vep);
> +
> +	fwnode_handle_put(ep_fwnode);
> +
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to parse sink endpoint");
> +
> +	num_data_lanes = vep.bus.mipi_csi2.num_data_lanes;
> +	if (num_data_lanes < 1 || num_data_lanes > 4)
> +		return dev_err_probe(dev, -EINVAL,
> +				     "Invalid data lanes must be 1 to 4\n");
> +
> +	memcpy(&priv->mipi_csi2, &vep.bus.mipi_csi2, sizeof(priv->mipi_csi2));

	priv->mipi_csi2 = vep.bus.mipi_csi2;

> +
> +	return 0;
> +}
> +
> +static int max96717_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct max96717_priv *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->client = client;
> +	priv->regmap = devm_cci_regmap_init_i2c(client, 16);
> +	if (IS_ERR(priv->regmap)) {
> +		ret = PTR_ERR(priv->regmap);
> +		return dev_err_probe(dev, ret, "Failed to init regmap\n");
> +	}
> +
> +	ret = max96717_parse_dt(priv);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to parse the dt\n");
> +
> +	ret = max96717_hw_init(priv);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to initialize the hardware\n");
> +
> +	ret = max96717_gpiochip_probe(priv);
> +	if (ret)
> +		return dev_err_probe(&client->dev, ret,
> +				     "Failed to init gpiochip\n");
> +
> +	ret = max96717_register_clkout(priv);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to register clkout\n");
> +
> +	ret = max96717_subdev_init(priv);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Failed to initialize v4l2 subdev\n");
> +
> +	ret = max96717_i2c_mux_init(priv);
> +	if (ret) {
> +		dev_err_probe(dev, ret, "failed to add remote i2c adapter\n");
> +		max96717_subdev_uninit(priv);
> +	}
> +
> +	return ret;
> +}
> +
> +static void max96717_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct max96717_priv *priv = sd_to_max96717(sd);
> +
> +	max96717_subdev_uninit(priv);
> +	i2c_mux_del_adapters(priv->mux);
> +}
> +
> +static const struct of_device_id max96717_of_ids[] = {
> +	{ .compatible = "maxim,max96717f" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, max96717_of_ids);
> +
> +static struct i2c_driver max96717_i2c_driver = {
> +	.driver	= {
> +		.name		= "max96717",
> +		.of_match_table	= max96717_of_ids,
> +	},
> +	.probe		= max96717_probe,
> +	.remove		= max96717_remove,
> +};
> +
> +module_i2c_driver(max96717_i2c_driver);
> +
> +MODULE_DESCRIPTION("Maxim GMSL2 MAX96717 Serializer Driver");
> +MODULE_AUTHOR("Julien Massot <julien.massot@collabora.com>");
> +MODULE_LICENSE("GPL");

-- 
Kind regards,

Sakari Ailus