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Message-ID: <4d349785-ca37-d930-db3c-2581bba9fde0@ideasonboard.com>
Date:   Wed, 14 Dec 2022 08:29:48 +0200
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Subject: Re: [PATCH v5 7/8] media: i2c: add DS90UB913 driver
Content-Language: en-US
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc:     linux-media@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Wolfram Sang <wsa@kernel.org>,
        Luca Ceresoli <luca.ceresoli@bootlin.com>,
        Andy Shevchenko <andriy.shevchenko@intel.com>,
        Matti Vaittinen <Matti.Vaittinen@fi.rohmeurope.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Peter Rosin <peda@axentia.se>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Michael Tretter <m.tretter@pengutronix.de>,
        Shawn Tu <shawnx.tu@intel.com>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        Mike Pagano <mpagano@gentoo.org>,
        =?UTF-8?Q?Krzysztof_Ha=c5=82asa?= <khalasa@piap.pl>,
        Marek Vasut <marex@denx.de>
References: <20221208104006.316606-1-tomi.valkeinen@ideasonboard.com>
 <20221208104006.316606-8-tomi.valkeinen@ideasonboard.com>
 <Y5YiazDtaxtLJyL0@pendragon.ideasonboard.com>
From:   Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
In-Reply-To: <Y5YiazDtaxtLJyL0@pendragon.ideasonboard.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

Hi Laurent,

On 11/12/2022 20:33, Laurent Pinchart wrote:
> Hi Tomi,
> 
> Thank you for the patch.
> 
> On Thu, Dec 08, 2022 at 12:40:05PM +0200, Tomi Valkeinen wrote:
>> Add driver for TI DS90UB913 FPDLink-3 Serializer.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> ---
>>   drivers/media/i2c/Kconfig     |  13 +
>>   drivers/media/i2c/Makefile    |   2 +-
>>   drivers/media/i2c/ds90ub913.c | 892 ++++++++++++++++++++++++++++++++++
>>   3 files changed, 906 insertions(+), 1 deletion(-)
>>   create mode 100644 drivers/media/i2c/ds90ub913.c
>>
>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>> index a23f723b89b5..ff5847aed5ae 100644
>> --- a/drivers/media/i2c/Kconfig
>> +++ b/drivers/media/i2c/Kconfig
>> @@ -1614,6 +1614,19 @@ config VIDEO_DS90UB960
>>   	  Device driver for the Texas Instruments DS90UB960
>>   	  FPD-Link III Deserializer
>>   
>> +config VIDEO_DS90UB913
>> +	tristate "TI DS90UB913 Serializer"
>> +	depends on OF && I2C && VIDEO_DEV
>> +	select MEDIA_CONTROLLER
>> +	select VIDEO_V4L2_SUBDEV_API
>> +	select V4L2_FWNODE
>> +	select REGMAP_I2C
>> +	select OF_GPIO
>> +	select I2C_ATR
>> +	help
>> +	  Device driver for the Texas Instruments DS90UB913
>> +	  FPD-Link III Serializer.
>> +
>>   endmenu
>>   
>>   endif # VIDEO_DEV
>> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
>> index 2735b00437bb..376886f2ded6 100644
>> --- a/drivers/media/i2c/Makefile
>> +++ b/drivers/media/i2c/Makefile
>> @@ -143,4 +143,4 @@ obj-$(CONFIG_VIDEO_VS6624) += vs6624.o
>>   obj-$(CONFIG_VIDEO_WM8739) += wm8739.o
>>   obj-$(CONFIG_VIDEO_WM8775) += wm8775.o
>>   obj-$(CONFIG_VIDEO_DS90UB960)	+= ds90ub960.o
>> -
>> +obj-$(CONFIG_VIDEO_DS90UB913)	+= ds90ub913.o
> 
> Alphabetical order please.

Ok.

>> diff --git a/drivers/media/i2c/ds90ub913.c b/drivers/media/i2c/ds90ub913.c
>> new file mode 100644
>> index 000000000000..6001a622e622
>> --- /dev/null
>> +++ b/drivers/media/i2c/ds90ub913.c
>> @@ -0,0 +1,892 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Driver for the Texas Instruments DS90UB913 video serializer
>> + *
>> + * Based on a driver from Luca Ceresoli <luca@lucaceresoli.net>
>> + *
>> + * Copyright (c) 2019 Luca Ceresoli <luca@lucaceresoli.net>
>> + * Copyright (c) 2022 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> + */
>> +
>> +#include <linux/clk-provider.h>
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/gpio/driver.h>
>> +#include <linux/i2c-atr.h>
>> +#include <linux/i2c.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_graph.h>
>> +#include <linux/regmap.h>
>> +
>> +#include <media/i2c/ds90ub9xx.h>
>> +#include <media/v4l2-subdev.h>
>> +
>> +#define UB913_PAD_SINK			0
>> +#define UB913_PAD_SOURCE		1
>> +
>> +/*
>> + * UB913 has 4 gpios, but gpios 3 and 4 are reserved for external oscillator
>> + * mode. Thus we only support 2 gpios for now.
>> + */
>> +#define UB913_NUM_GPIOS			2
>> +
>> +#define UB913_REG_RESET_CTL			0x01
>> +#define UB913_REG_RESET_CTL_DIGITAL_RESET_1	BIT(1)
>> +#define UB913_REG_RESET_CTL_DIGITAL_RESET_0	BIT(0)
>> +
>> +#define UB913_REG_GENERAL_CFG			0x03
>> +#define UB913_REG_MODE_SEL			0x05
>> +
>> +#define UB913_REG_CRC_ERRORS_LSB		0x0a
>> +#define UB913_REG_CRC_ERRORS_MSB		0x0b
>> +
>> +#define UB913_REG_GENERAL_STATUS		0x0c
>> +
>> +#define UB913_REG_GPIO_CFG(n)			(0x0d + (n))
>> +#define UB913_REG_GPIO_CFG_ENABLE(n)		BIT(0 + (n) * 4)
>> +#define UB913_REG_GPIO_CFG_DIR_INPUT(n)		BIT(1 + (n) * 4)
>> +#define UB913_REG_GPIO_CFG_REMOTE_EN(n)		BIT(2 + (n) * 4)
>> +#define UB913_REG_GPIO_CFG_OUT_VAL(n)		BIT(3 + (n) * 4)
>> +#define UB913_REG_GPIO_CFG_MASK(n)		(0xf << ((n) * 4))
>> +
>> +#define UB913_REG_SCL_HIGH_TIME			0x11
>> +#define UB913_REG_SCL_LOW_TIME			0x12
>> +
>> +#define UB913_REG_PLL_OVR			0x35
>> +
>> +struct ub913_data {
>> +	struct i2c_client	*client;
>> +	struct regmap		*regmap;
>> +	struct clk		*clkin;
>> +
>> +	u32			gpio_func[UB913_NUM_GPIOS];
>> +
>> +	struct gpio_chip	gpio_chip;
>> +	char			gpio_chip_name[64];
>> +
>> +	struct v4l2_subdev	sd;
>> +	struct media_pad	pads[2];
>> +
>> +	struct v4l2_async_notifier	notifier;
>> +
>> +	struct v4l2_subdev	*source_sd;
>> +
>> +	u64			enabled_source_streams;
>> +
>> +	struct device_node	*tx_ep_np;
>> +
>> +	struct clk_hw		*clkout_clk_hw;
>> +
>> +	struct ds90ub9xx_platform_data *plat_data;
>> +
>> +	/* Have we succefully called i2c_atr_add_adapter() */
>> +	bool			has_i2c_adapter;
>> +};
>> +
>> +static inline struct ub913_data *sd_to_ub913(struct v4l2_subdev *sd)
>> +{
>> +	return container_of(sd, struct ub913_data, sd);
>> +}
>> +
>> +static int ub913_read(const struct ub913_data *priv, u8 reg, u8 *val)
>> +{
>> +	unsigned int v;
>> +	int ret;
>> +
>> +	ret = regmap_read(priv->regmap, reg, &v);
>> +	if (ret < 0) {
>> +		dev_err(&priv->client->dev,
>> +			"Cannot read register 0x%02x: %d!\n", reg, ret);
>> +		return ret;
>> +	}
>> +
>> +	*val = v;
>> +	return 0;
>> +}
>> +
>> +static int ub913_write(const struct ub913_data *priv, u8 reg, u8 val)
>> +{
>> +	int ret;
>> +
>> +	ret = regmap_write(priv->regmap, reg, val);
>> +	if (ret < 0)
>> +		dev_err(&priv->client->dev,
>> +			"Cannot write register 0x%02x: %d!\n", reg, ret);
>> +
>> +	return ret;
>> +}
>> +
>> +/*
>> + * GPIO chip
>> + */
>> +static int ub913_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
>> +{
>> +	return GPIO_LINE_DIRECTION_OUT;
>> +}
>> +
>> +static int ub913_gpio_direction_out(struct gpio_chip *gc, unsigned int offset,
>> +				    int value)
>> +{
>> +	struct ub913_data *priv = gpiochip_get_data(gc);
>> +	unsigned int reg_idx;
>> +	unsigned int field_idx;
>> +	int ret;
>> +
>> +	reg_idx = offset / 2;
>> +	field_idx = offset % 2;
>> +
>> +	ret = regmap_update_bits(
>> +		priv->regmap, UB913_REG_GPIO_CFG(reg_idx),
>> +		UB913_REG_GPIO_CFG_MASK(field_idx),
>> +		UB913_REG_GPIO_CFG_ENABLE(field_idx) |
>> +			(value ? UB913_REG_GPIO_CFG_OUT_VAL(field_idx) : 0));
>> +
>> +	return ret;
>> +}
>> +
>> +static void ub913_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
>> +{
>> +	ub913_gpio_direction_out(gc, offset, value);
>> +}
>> +
>> +static int ub913_gpio_of_xlate(struct gpio_chip *gc,
>> +			       const struct of_phandle_args *gpiospec,
>> +			       u32 *flags)
>> +{
>> +	if (flags)
>> +		*flags = gpiospec->args[1];
>> +
>> +	return gpiospec->args[0];
>> +}
>> +
>> +static int ub913_gpiochip_probe(struct ub913_data *priv)
>> +{
>> +	struct device *dev = &priv->client->dev;
>> +	struct gpio_chip *gc = &priv->gpio_chip;
>> +	int ret;
>> +
>> +	/* Initialize GPIOs 0 and 1 to local control, tri-state */
>> +	ub913_write(priv, UB913_REG_GPIO_CFG(0), 0);
>> +
>> +	scnprintf(priv->gpio_chip_name, sizeof(priv->gpio_chip_name), "%s",
>> +		  dev_name(dev));
>> +
>> +	gc->label = priv->gpio_chip_name;
>> +	gc->parent = dev;
>> +	gc->owner = THIS_MODULE;
>> +	gc->base = -1;
>> +	gc->can_sleep = 1;
>> +	gc->ngpio = UB913_NUM_GPIOS;
>> +	gc->get_direction = ub913_gpio_get_direction;
>> +	gc->direction_output = ub913_gpio_direction_out;
>> +	gc->set = ub913_gpio_set;
>> +	gc->of_xlate = ub913_gpio_of_xlate;
>> +	gc->of_node = priv->client->dev.of_node;
>> +	gc->of_gpio_n_cells = 2;
>> +
>> +	ret = gpiochip_add_data(gc, priv);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to add GPIOs: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void ub913_gpiochip_remove(struct ub913_data *priv)
>> +{
>> +	gpiochip_remove(&priv->gpio_chip);
>> +}
>> +
>> +static int ub913_parse_dt(struct ub913_data *priv)
> 
> I would have moved this just before ub913_probe().

Sure.

>> +{
>> +	struct device_node *np = priv->client->dev.of_node;
>> +	struct device *dev = &priv->client->dev;
>> +	int ret;
>> +
>> +	if (!np) {
>> +		dev_err(dev, "OF: no device tree node!\n");
>> +		return -ENOENT;
>> +	}
>> +
>> +	/* optional, if absent all GPIO pins are unused */
>> +	ret = of_property_read_u32_array(np, "gpio-functions", priv->gpio_func,
>> +					 ARRAY_SIZE(priv->gpio_func));
>> +	if (ret && ret != -EINVAL)
>> +		dev_err(dev, "DT: invalid gpio-functions property (%d)", ret);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct regmap_config ub913_regmap_config = {
>> +	.name = "ds90ub913",
>> +	.reg_bits = 8,
>> +	.val_bits = 8,
>> +	.reg_format_endian = REGMAP_ENDIAN_DEFAULT,
>> +	.val_format_endian = REGMAP_ENDIAN_DEFAULT,
>> +};
>> +
>> +/*
>> + * V4L2
>> + */
>> +
>> +static int ub913_enable_streams(struct v4l2_subdev *sd,
>> +				struct v4l2_subdev_state *state, u32 pad,
>> +				u64 streams_mask)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(sd);
>> +	struct media_pad *remote_pad;
>> +	u64 sink_streams;
>> +	int ret;
>> +
>> +	if (streams_mask & priv->enabled_source_streams)
>> +		return -EALREADY;
>> +
>> +	sink_streams = v4l2_subdev_state_xlate_streams(
>> +		state, UB913_PAD_SOURCE, UB913_PAD_SINK, &streams_mask);
>> +
>> +	remote_pad = media_pad_remote_pad_first(&priv->pads[UB913_PAD_SINK]);
>> +
>> +	ret = v4l2_subdev_enable_streams(priv->source_sd, remote_pad->index,
>> +					 sink_streams);
>> +	if (ret)
>> +		return ret;
>> +
>> +	priv->enabled_source_streams |= streams_mask;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ub913_disable_streams(struct v4l2_subdev *sd,
>> +				 struct v4l2_subdev_state *state, u32 pad,
>> +				 u64 streams_mask)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(sd);
>> +	struct media_pad *remote_pad;
>> +	int ret;
>> +	u64 sink_streams;
>> +
>> +	if ((streams_mask & priv->enabled_source_streams) != streams_mask)
>> +		return -EALREADY;
>> +
>> +	sink_streams = v4l2_subdev_state_xlate_streams(
>> +		state, UB913_PAD_SOURCE, UB913_PAD_SINK, &streams_mask);
>> +
>> +	remote_pad = media_pad_remote_pad_first(&priv->pads[UB913_PAD_SINK]);
>> +
>> +	ret = v4l2_subdev_disable_streams(priv->source_sd, remote_pad->index,
>> +					  sink_streams);
>> +	if (ret)
>> +		return ret;
>> +
>> +	priv->enabled_source_streams &= ~streams_mask;
>> +
>> +	return 0;
>> +}
>> +
>> +static int _ub913_set_routing(struct v4l2_subdev *sd,
>> +			      struct v4l2_subdev_state *state,
>> +			      struct v4l2_subdev_krouting *routing)
>> +{
>> +	const struct v4l2_mbus_framefmt format = {
> 
> static

Yep.

>> +		.width = 640,
>> +		.height = 480,
>> +		.code = MEDIA_BUS_FMT_UYVY8_2X8,
>> +		.field = V4L2_FIELD_NONE,
>> +		.colorspace = V4L2_COLORSPACE_SRGB,
>> +		.ycbcr_enc = V4L2_YCBCR_ENC_601,
>> +		.quantization = V4L2_QUANTIZATION_LIM_RANGE,
>> +		.xfer_func = V4L2_XFER_FUNC_SRGB,
>> +	};
>> +	int ret;
>> +
>> +	/*
>> +	 * Note: we can only support up to V4L2_FRAME_DESC_ENTRY_MAX, until
>> +	 * frame desc is made dynamically allocated.
>> +	 */
>> +
>> +	if (routing->num_routes > V4L2_FRAME_DESC_ENTRY_MAX)
>> +		return -EINVAL;
>> +
>> +	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 ub913_set_routing(struct v4l2_subdev *sd,
>> +			     struct v4l2_subdev_state *state,
>> +			     enum v4l2_subdev_format_whence which,
>> +			     struct v4l2_subdev_krouting *routing)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(sd);
>> +
>> +	if (which == V4L2_SUBDEV_FORMAT_ACTIVE && priv->enabled_source_streams)
>> +		return -EBUSY;
>> +
>> +	return _ub913_set_routing(sd, state, routing);
>> +}
>> +
>> +static int ub913_get_source_frame_desc(struct ub913_data *priv,
>> +				       struct v4l2_mbus_frame_desc *desc)
>> +{
>> +	struct media_pad *pad;
>> +	int ret;
>> +
>> +	pad = media_pad_remote_pad_first(&priv->pads[UB913_PAD_SINK]);
>> +	if (!pad)
>> +		return -EPIPE;
>> +
>> +	ret = v4l2_subdev_call(priv->source_sd, pad, get_frame_desc, pad->index,
>> +			       desc);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
> 
> I would inline this in the caller.

Well... Having it separate doesn't provide too much benefit, but it does 
make it a bit cleaner as we don't need to play with the 'unsigned int 
pad' and the 'struct media_pad *pad' in the same function.

>> +}
>> +
>> +static int ub913_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
>> +				struct v4l2_mbus_frame_desc *fd)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(sd);
>> +	const struct v4l2_subdev_krouting *routing;
>> +	struct v4l2_mbus_frame_desc source_fd;
>> +	struct v4l2_subdev_route *route;
>> +	struct v4l2_subdev_state *state;
>> +	int ret = 0;
> 
> No need to initialize this to 0.

Yep.

>> +
>> +	if (pad != 1) /* first tx pad */
> 
> 	if (pad != UB913_PAD_SOURCE)
> 
> and drop the comment.

Yep.

>> +		return -EINVAL;
>> +
>> +	ret = ub913_get_source_frame_desc(priv, &source_fd);
>> +	if (ret)
>> +		return ret;
>> +
>> +	state = v4l2_subdev_lock_and_get_active_state(sd);
>> +
>> +	routing = &state->routing;
>> +
>> +	memset(fd, 0, sizeof(*fd));
>> +
>> +	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL;
>> +
>> +	for_each_active_route(routing, route) {
>> +		unsigned int j;
> 
> Anything wrong with 'i' ?

I'm pretty sure it was reserved for the route iteration, before we had 
for_each_active_route() =).

>> +
>> +		if (route->source_pad != pad)
>> +			continue;
>> +
>> +		for (j = 0; j < source_fd.num_entries; ++j)
>> +			if (source_fd.entry[j].stream == route->sink_stream)
>> +				break;
>> +
>> +		if (j == source_fd.num_entries) {
>> +			dev_err(&priv->client->dev,
>> +				"Failed to find stream from source frame desc\n");
>> +			ret = -EPIPE;
>> +			goto out;
>> +		}
>> +
>> +		fd->entry[fd->num_entries].stream = route->source_stream;
>> +
>> +		fd->entry[fd->num_entries].flags =
>> +			V4L2_MBUS_FRAME_DESC_FL_LEN_MAX;
> 
> Shouldn't this be set only if set in the source frame descriptor ?

Yes... I seem to be doing the same in the other ub9xx drivers. I'm not 
sure where this came originally.

>> +		fd->entry[fd->num_entries].length = source_fd.entry[j].length;
>> +		fd->entry[fd->num_entries].pixelcode =
>> +			source_fd.entry[j].pixelcode;
>> +
>> +		fd->num_entries++;
>> +	}
>> +
>> +out:
>> +	v4l2_subdev_unlock_state(state);
>> +
>> +	return ret;
>> +}
>> +
>> +static int ub913_set_fmt(struct v4l2_subdev *sd,
>> +			 struct v4l2_subdev_state *state,
>> +			 struct v4l2_subdev_format *format)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(sd);
>> +	struct v4l2_mbus_framefmt *fmt;
>> +
>> +	if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE &&
>> +	    priv->enabled_source_streams)
>> +		return -EBUSY;
>> +
>> +	/* No transcoding, source and sink formats must match. */
>> +	if (format->pad == 1)
> 
> 	if (format->pad == UB913_PAD_SOURCE)

Yep.

>> +		return v4l2_subdev_get_fmt(sd, state, format);
>> +
>> +	/* Set sink format */
>> +	fmt = v4l2_subdev_state_get_stream_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;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ub913_init_cfg(struct v4l2_subdev *sd,
>> +			  struct v4l2_subdev_state *state)
>> +{
>> +	struct v4l2_subdev_route routes[] = {
>> +		{
>> +			.sink_pad = 0,
> 
> 			.sink_pad = UB913_PAD_SINK,
> 
>> +			.sink_stream = 0,
>> +			.source_pad = 1,
> 
> 			.source_pad = UB913_PAD_SOURCE,

Yep.

>> +			.source_stream = 0,
>> +			.flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE,
>> +		},
>> +	};
>> +
>> +	struct v4l2_subdev_krouting routing = {
>> +		.num_routes = ARRAY_SIZE(routes),
>> +		.routes = routes,
>> +	};
>> +
>> +	return _ub913_set_routing(sd, state, &routing);
>> +}
>> +
>> +static int ub913_log_status(struct v4l2_subdev *sd)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(sd);
>> +	struct device *dev = &priv->client->dev;
>> +	u8 v, v1, v2;
>> +
>> +	ub913_read(priv, UB913_REG_MODE_SEL, &v);
>> +	dev_info(dev, "MODE_SEL %#x\n", v);
>> +
>> +	ub913_read(priv, UB913_REG_CRC_ERRORS_LSB, &v1);
>> +	ub913_read(priv, UB913_REG_CRC_ERRORS_MSB, &v2);
>> +	dev_info(dev, "CRC errors %u\n", v1 | (v2 << 8));
>> +
>> +	ub913_read(priv, UB913_REG_GENERAL_STATUS, &v);
>> +	dev_info(dev, "GENERAL_STATUS %#x\n", v);
>> +
>> +	ub913_read(priv, UB913_REG_PLL_OVR, &v);
>> +	dev_info(dev, "PLL_OVR %#x\n", v);
>> +
>> +	/* clear CRC errors */
>> +	ub913_read(priv, UB913_REG_GENERAL_CFG, &v);
>> +	ub913_write(priv, UB913_REG_GENERAL_CFG, v | BIT(5));
>> +	ub913_write(priv, UB913_REG_GENERAL_CFG, v);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct v4l2_subdev_core_ops ub913_subdev_core_ops = {
>> +	.log_status = ub913_log_status,
>> +};
>> +
>> +static const struct v4l2_subdev_pad_ops ub913_pad_ops = {
>> +	.enable_streams = ub913_enable_streams,
>> +	.disable_streams = ub913_disable_streams,
>> +	.set_routing = ub913_set_routing,
>> +	.get_frame_desc	= ub913_get_frame_desc,
>> +	.get_fmt = v4l2_subdev_get_fmt,
>> +	.set_fmt = ub913_set_fmt,
>> +	.init_cfg = ub913_init_cfg,
>> +};
>> +
>> +static const struct v4l2_subdev_ops ub913_subdev_ops = {
>> +	.core = &ub913_subdev_core_ops,
>> +	.pad = &ub913_pad_ops,
>> +};
>> +
>> +static const struct media_entity_operations ub913_entity_ops = {
>> +	.link_validate = v4l2_subdev_link_validate,
>> +};
>> +
>> +static int ub913_notify_bound(struct v4l2_async_notifier *notifier,
>> +			      struct v4l2_subdev *source_subdev,
>> +			      struct v4l2_async_subdev *asd)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(notifier->sd);
>> +	struct device *dev = &priv->client->dev;
>> +	unsigned int src_pad;
>> +	int ret;
>> +
>> +	dev_dbg(dev, "Bind %s\n", source_subdev->name);
> 
> I'd drop this message.

Why is that? Do we get this easily from the v4l2 core? These debug 
prints in the bind/unbind process have been valuable for me.

>> +
>> +	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;
>> +	src_pad = ret;
>> +
>> +	ret = media_create_pad_link(&source_subdev->entity, src_pad,
>> +				    &priv->sd.entity, 0,
> 
> 				    &priv->sd.entity, UB913_PAD_SINK,

Yep.

>> +				    MEDIA_LNK_FL_ENABLED |
>> +				    MEDIA_LNK_FL_IMMUTABLE);
>> +	if (ret) {
>> +		dev_err(dev, "Unable to link %s:%u -> %s:0\n",
>> +			source_subdev->name, src_pad, priv->sd.name);
>> +		return ret;
>> +	}
>> +
>> +	dev_dbg(dev, "Bound %s:%u\n", source_subdev->name, src_pad);
>> +
>> +	dev_dbg(dev, "All subdevs bound\n");
> 
> I'd drop this message.
> 
>> +
>> +	return 0;
>> +}
>> +
>> +static void ub913_notify_unbind(struct v4l2_async_notifier *notifier,
>> +				struct v4l2_subdev *source_subdev,
>> +				struct v4l2_async_subdev *asd)
>> +{
>> +	struct ub913_data *priv = sd_to_ub913(notifier->sd);
>> +	struct device *dev = &priv->client->dev;
>> +
>> +	dev_dbg(dev, "Unbind %s\n", source_subdev->name);
>> +}
> 
> This is a no-op so you can drop it.

This has been useful for development, but, yes, perhaps it's time to 
drop it.

>> +
>> +static const struct v4l2_async_notifier_operations ub913_notify_ops = {
>> +	.bound = ub913_notify_bound,
>> +	.unbind = ub913_notify_unbind,
>> +};
>> +
>> +static int ub913_v4l2_notifier_register(struct ub913_data *priv)
>> +{
>> +	struct device *dev = &priv->client->dev;
>> +	struct v4l2_async_subdev *asd;
>> +	struct device_node *ep_node;
>> +	int ret;
>> +
>> +	dev_dbg(dev, "register async notif\n");
>> +
>> +	ep_node = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
>> +	if (!ep_node) {
>> +		dev_err(dev, "No graph endpoint\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	v4l2_async_nf_init(&priv->notifier);
>> +
>> +	asd = v4l2_async_nf_add_fwnode_remote(&priv->notifier,
>> +					      of_fwnode_handle(ep_node),
>> +					      struct v4l2_async_subdev);
>> +
>> +	of_node_put(ep_node);
>> +
>> +	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 = &ub913_notify_ops;
>> +
>> +	ret = v4l2_async_subdev_nf_register(&priv->sd, &priv->notifier);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to register subdev_notifier");
>> +		v4l2_async_nf_cleanup(&priv->notifier);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void ub913_v4l2_nf_unregister(struct ub913_data *priv)
>> +{
>> +	struct device *dev = &priv->client->dev;
>> +
>> +	dev_dbg(dev, "Unregister async notif\n");
>> +
>> +	v4l2_async_nf_unregister(&priv->notifier);
>> +	v4l2_async_nf_cleanup(&priv->notifier);
>> +}
>> +
>> +static int ub913_register_clkout(struct ub913_data *priv)
>> +{
>> +	struct device *dev = &priv->client->dev;
>> +	const char *name;
>> +	int ret;
>> +
>> +	name = kasprintf(GFP_KERNEL, "ds90ub913.%s.clk_out", dev_name(dev));
>> +
>> +	priv->clkout_clk_hw = devm_clk_hw_register_fixed_factor(dev, name,
>> +		__clk_get_name(priv->clkin), 0, 1, 2);
>> +
>> +	kfree(name);
>> +
>> +	if (IS_ERR(priv->clkout_clk_hw))
>> +		return dev_err_probe(dev, PTR_ERR(priv->clkout_clk_hw),
>> +				     "Cannot register clkout hw\n");
>> +
>> +	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
>> +					  priv->clkout_clk_hw);
>> +	if (ret)
>> +		return dev_err_probe(dev, ret,
>> +				     "Cannot add OF clock provider\n");
>> +
>> +	return 0;
>> +}
>> +
>> +static int ub913_i2c_master_init(struct ub913_data *priv)
>> +{
>> +	/* i2c fast mode */
>> +	u32 scl_high = 600 + 300; /* high period + rise time, ns */
>> +	u32 scl_low = 1300 + 300; /* low period + fall time, ns */
>> +	unsigned long ref;
>> +	int ret;
>> +
>> +	ref = clk_get_rate(priv->clkin) / 2;
>> +
>> +	scl_high = div64_u64((u64)scl_high * ref, 1000000000);
>> +	scl_low = div64_u64((u64)scl_low * ref, 1000000000);
>> +
>> +	ret = ub913_write(priv, UB913_REG_SCL_HIGH_TIME, scl_high);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = ub913_write(priv, UB913_REG_SCL_LOW_TIME, scl_low);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ub913_add_i2c_adapter(struct ub913_data *priv)
>> +{
>> +	struct device *dev = &priv->client->dev;
>> +	struct fwnode_handle *i2c_handle;
>> +	int ret;
>> +
>> +	i2c_handle = device_get_named_child_node(dev, "i2c");
>> +	if (!i2c_handle)
>> +		return 0;
>> +
>> +	ret = i2c_atr_add_adapter(priv->plat_data->atr, priv->plat_data->port,
>> +				  i2c_handle);
>> +
>> +	fwnode_handle_put(i2c_handle);
>> +
>> +	if (ret)
>> +		return ret;
>> +
>> +	priv->has_i2c_adapter = true;
>> +
>> +	return 0;
>> +}
>> +
>> +static void ub913_remove_i2c_adapter(struct ub913_data *priv)
>> +{
>> +	if (priv->has_i2c_adapter)
>> +		i2c_atr_del_adapter(priv->plat_data->atr,
>> +				    priv->plat_data->port);
> 
> Could i2c_atr_del_adapter() be a no-op if no adapter for the port has
> been added ? You could then drop the has_i2c_adapter field. I'm also

Yes, I think that'd be fine.

> wondering if the struct device of the DS90UB913 could be passed instead
> of the port, to avoid passing the port throught
> ds90ub9xx_platform_data.

Interesting thought. That would limit the number of remote i2c busses to 
one, though. Not a problem for FPD-Link, but I wonder if that's assuming 
too much for the future users. Then again, this is an in-kernel API so 
we could extend it later if needed. So I'll try this out and see if I 
hit any issues.

>> +}
>> +
>> +static int ub913_probe(struct i2c_client *client)
>> +{
>> +	struct device *dev = &client->dev;
>> +	struct ub913_data *priv;
>> +	int ret;
>> +	u8 v;
>> +	bool mode_override;
>> +	u8 mode;
>> +
>> +	dev_dbg(dev, "probing, addr 0x%02x\n", client->addr);
>> +
>> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	priv->client = client;
>> +
>> +	priv->plat_data = dev_get_platdata(&client->dev);
>> +	if (!priv->plat_data) {
>> +		dev_err(dev, "Platform data missing\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	priv->regmap = devm_regmap_init_i2c(client, &ub913_regmap_config);
>> +	if (IS_ERR(priv->regmap)) {
>> +		dev_err(dev, "Failed to init regmap\n");
>> +		return PTR_ERR(priv->regmap);
>> +	}
>> +
>> +	/* ub913 can also work without ext clock, but that is not supported */
>> +	priv->clkin = devm_clk_get(dev, "clkin");
>> +	if (IS_ERR(priv->clkin)) {
>> +		ret = PTR_ERR(priv->clkin);
>> +		if (ret != -EPROBE_DEFER)
>> +			dev_err(dev, "Cannot get CLKIN (%d)", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = ub913_parse_dt(priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = ub913_read(priv, UB913_REG_MODE_SEL, &v);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (!(v & BIT(4))) {
> 
> Please add a mcro for this. Same for other magic bits in the driver.

Sure.

>> +		dev_err(dev, "Mode value not stabilized\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	mode_override = v & BIT(5);
>> +	mode = v & 0xf;
>> +
>> +	dev_dbg(dev, "mode from %s: %#x\n",
>> +		mode_override ? "reg" : "deserializer", mode);
>> +
>> +	ret = ub913_i2c_master_init(priv);
>> +	if (ret) {
>> +		dev_err(dev, "i2c master init failed: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = ub913_gpiochip_probe(priv);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to init gpiochip\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = ub913_register_clkout(priv);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to register clkout\n");
>> +		goto err_gpiochip_remove;
>> +	}
>> +
>> +	v4l2_i2c_subdev_init(&priv->sd, priv->client, &ub913_subdev_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 = &ub913_entity_ops;
>> +
>> +	priv->pads[0].flags = MEDIA_PAD_FL_SINK;
>> +	priv->pads[1].flags = MEDIA_PAD_FL_SOURCE;
>> +
>> +	ret = media_entity_pads_init(&priv->sd.entity, 2, priv->pads);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to init pads\n");
>> +		goto err_gpiochip_remove;
>> +	}
>> +
>> +	priv->tx_ep_np = of_graph_get_endpoint_by_regs(dev->of_node, 1, 0);
>> +	if (priv->tx_ep_np)
>> +		priv->sd.fwnode = of_fwnode_handle(priv->tx_ep_np);
>> +
>> +	ret = v4l2_subdev_init_finalize(&priv->sd);
>> +	if (ret)
>> +		goto err_entity_cleanup;
>> +
>> +	ret = ub913_v4l2_notifier_register(priv);
>> +	if (ret) {
>> +		dev_err(dev, "v4l2 subdev notifier register failed: %d\n", ret);
>> +		goto err_free_state;
>> +	}
>> +
>> +	ret = v4l2_async_register_subdev(&priv->sd);
>> +	if (ret) {
>> +		dev_err(dev, "v4l2_async_register_subdev error: %d\n", ret);
>> +		goto err_unreg_notif;
>> +	}
>> +
>> +	ret = ub913_add_i2c_adapter(priv);
>> +	if (ret) {
>> +		dev_err(dev, "failed to add remote i2c adapter\n");
>> +		goto err_unreg_async_subdev;
>> +	}
>> +
>> +	dev_dbg(dev, "Successfully probed\n");
>> +
>> +	return 0;
>> +
>> +err_unreg_async_subdev:
>> +	v4l2_async_unregister_subdev(&priv->sd);
>> +err_unreg_notif:
>> +	ub913_v4l2_nf_unregister(priv);
>> +err_free_state:
>> +	v4l2_subdev_cleanup(&priv->sd);
>> +err_entity_cleanup:
>> +	if (priv->tx_ep_np)
>> +		of_node_put(priv->tx_ep_np);
>> +
>> +	media_entity_cleanup(&priv->sd.entity);
>> +err_gpiochip_remove:
>> +	ub913_gpiochip_remove(priv);
>> +
>> +	return ret;
>> +}
>> +
>> +static void ub913_remove(struct i2c_client *client)
>> +{
>> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
>> +	struct ub913_data *priv = sd_to_ub913(sd);
>> +
>> +	dev_dbg(&client->dev, "Removing\n");
>> +
>> +	ub913_remove_i2c_adapter(priv);
>> +
>> +	v4l2_async_unregister_subdev(&priv->sd);
>> +
>> +	ub913_v4l2_nf_unregister(priv);
>> +
>> +	v4l2_subdev_cleanup(&priv->sd);
>> +
>> +	if (priv->tx_ep_np)
>> +		of_node_put(priv->tx_ep_np);
>> +
>> +	media_entity_cleanup(&priv->sd.entity);
>> +
>> +	ub913_gpiochip_remove(priv);
>> +}
>> +
>> +static const struct i2c_device_id ub913_id[] = { { "ds90ub913a-q1", 0 }, {} };
>> +MODULE_DEVICE_TABLE(i2c, ub913_id);
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id ub913_dt_ids[] = {
>> +	{ .compatible = "ti,ds90ub913a-q1", },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, ub913_dt_ids);
>> +#endif
>> +
>> +static struct i2c_driver ds90ub913_driver = {
>> +	.probe_new	= ub913_probe,
>> +	.remove		= ub913_remove,
>> +	.id_table	= ub913_id,
>> +	.driver = {
>> +		.name	= "ds90ub913a",
>> +		.owner = THIS_MODULE,
>> +		.of_match_table = of_match_ptr(ub913_dt_ids),
>> +	},
>> +};
>> +
>> +module_i2c_driver(ds90ub913_driver);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_DESCRIPTION("Texas Instruments DS90UB913 serializer driver");
>> +MODULE_AUTHOR("Luca Ceresoli <luca@lucaceresoli.net>");
>> +MODULE_AUTHOR("Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>");
>> -- 
>> 2.34.1
>>
>