Re: [PATCH v1 11/15] media: i2c: imx290: Use V4L2 subdev active state

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

Hi Alexander,

On Wed, Nov 23, 2022 at 09:42:10AM +0100, Alexander Stein wrote:
> Am Dienstag, 22. November 2022, 23:32:46 CET schrieb Laurent Pinchart:
> > Use the V4L2 subdev active state API to store the active format. This
> > simplifies the driver not only by dropping the imx290 current_format
> > field, but it also allows dropping the imx290 lock, replaced with the
> > state lock.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> >  drivers/media/i2c/imx290.c | 139 +++++++++++++++----------------------
> >  1 file changed, 56 insertions(+), 83 deletions(-)
> > 
> > diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
> > index 848de4c90d3b..cd2154983341 100644
> > --- a/drivers/media/i2c/imx290.c
> > +++ b/drivers/media/i2c/imx290.c
> > @@ -177,12 +177,12 @@ struct imx290 {
> >  	struct clk *xclk;
> >  	struct regmap *regmap;
> >  	u8 nlanes;
> > -	u8 bpp;
> > 
> >  	struct v4l2_subdev sd;
> >  	struct media_pad pad;
> > -	struct v4l2_mbus_framefmt current_format;
> > +
> >  	const struct imx290_mode *current_mode;
> > +	u8 bpp;
> > 
> >  	struct regulator_bulk_data supplies[IMX290_NUM_SUPPLIES];
> >  	struct gpio_desc *rst_gpio;
> > @@ -192,8 +192,6 @@ struct imx290 {
> >  	struct v4l2_ctrl *pixel_rate;
> >  	struct v4l2_ctrl *hblank;
> >  	struct v4l2_ctrl *vblank;
> > -
> > -	struct mutex lock;
> >  };
> > 
> >  static inline struct imx290 *to_imx290(struct v4l2_subdev *_sd)
> > @@ -524,14 +522,15 @@ static int imx290_set_black_level(struct imx290
> > *imx290, black_level >> (16 - imx290->bpp), err);
> >  }
> > 
> > -static int imx290_write_current_format(struct imx290 *imx290)
> > +static int imx290_setup_format(struct imx290 *imx290,
> > +			       const struct v4l2_mbus_framefmt *format)
> >  {
> >  	const struct imx290_regval *regs;
> >  	unsigned int num_regs;
> >  	unsigned int bpp;
> >  	int ret;
> > 
> > -	switch (imx290->current_format.code) {
> > +	switch (format->code) {
> >  	case MEDIA_BUS_FMT_SRGGB10_1X10:
> >  		regs = imx290_10bit_settings;
> >  		num_regs = ARRAY_SIZE(imx290_10bit_settings);
> > @@ -564,12 +563,17 @@ static int imx290_set_ctrl(struct v4l2_ctrl *ctrl)
> >  {
> >  	struct imx290 *imx290 = container_of(ctrl->handler,
> >  					     struct imx290, ctrls);
> > +	const struct v4l2_mbus_framefmt *format;
> > +	struct v4l2_subdev_state *state;
> >  	int ret = 0;
> > 
> >  	/* V4L2 controls values will be applied only when power is already up */
> >  	if (!pm_runtime_get_if_in_use(imx290->dev))
> >  		return 0;
> > 
> > +	state = v4l2_subdev_get_locked_active_state(&imx290->sd);
> > +	format = v4l2_subdev_get_pad_format(&imx290->sd, state, 0);
> > +
> >  	switch (ctrl->id) {
> >  	case V4L2_CID_ANALOGUE_GAIN:
> >  		ret = imx290_write(imx290, IMX290_GAIN, ctrl->val, NULL);
> > @@ -646,11 +650,10 @@ static int imx290_ctrl_init(struct imx290 *imx290)
> >  	int ret;
> > 
> >  	ret = v4l2_fwnode_device_parse(imx290->dev, &props);
> > -	if (ret < 0)
> > +	if (ret)
> 
> This is an unrelated change.

I'll drop it.

> >  		return ret;
> > 
> >  	v4l2_ctrl_handler_init(&imx290->ctrls, 9);
> > -	imx290->ctrls.lock = &imx290->lock;
> > 
> >  	/*
> >  	 * The sensor has an analog gain and a digital gain, both controlled
> > @@ -715,11 +718,6 @@ static int imx290_ctrl_init(struct imx290 *imx290)
> >  		return ret;
> >  	}
> > 
> > -	mutex_lock(imx290->ctrls.lock);
> > -	imx290_ctrl_update(imx290, &imx290->current_format,
> > -			   imx290->current_mode);
> > -	mutex_unlock(imx290->ctrls.lock);
> > -
> >  	return 0;
> >  }
> > 
> > @@ -728,8 +726,10 @@ static int imx290_ctrl_init(struct imx290 *imx290)
> >   */
> > 
> >  /* Start streaming */
> > -static int imx290_start_streaming(struct imx290 *imx290)
> > +static int imx290_start_streaming(struct imx290 *imx290,
> > +				  struct v4l2_subdev_state *state)
> >  {
> > +	const struct v4l2_mbus_framefmt *format;
> >  	int ret;
> > 
> >  	/* Set init register settings */
> > @@ -742,7 +742,8 @@ static int imx290_start_streaming(struct imx290 *imx290)
> > }
> > 
> >  	/* Apply the register values related to current frame format */
> > -	ret = imx290_write_current_format(imx290);
> > +	format = v4l2_subdev_get_pad_format(&imx290->sd, state, 0);
> > +	ret = imx290_setup_format(imx290, format);
> >  	if (ret < 0) {
> >  		dev_err(imx290->dev, "Could not set frame format\n");
> >  		return ret;
> > @@ -762,7 +763,7 @@ static int imx290_start_streaming(struct imx290 *imx290)
> > return ret;
> > 
> >  	/* Apply customized values from user */
> > -	ret = v4l2_ctrl_handler_setup(imx290->sd.ctrl_handler);
> > +	ret = __v4l2_ctrl_handler_setup(imx290->sd.ctrl_handler);
> 
> Why is it safe to ignore the lock now? There is no user-specified lock for 
> imx290->ctrls.lock, but instead imx290->ctrls._lock is set, no?

That's because the control handler and subdev state lock are the same.
The imx290_start_streaming() function starts by calling
v4l2_subdev_lock_and_get_active_state(), which takes the lock, so we
must not lock again with v4l2_ctrl_handler_setup().

> >  	if (ret) {
> >  		dev_err(imx290->dev, "Could not sync v4l2 controls\n");
> >  		return ret;
> > @@ -791,39 +792,32 @@ static int imx290_stop_streaming(struct imx290
> > *imx290) static int imx290_set_stream(struct v4l2_subdev *sd, int enable)
> >  {
> >  	struct imx290 *imx290 = to_imx290(sd);
> > +	struct v4l2_subdev_state *state;
> >  	int ret = 0;
> > 
> > +	state = v4l2_subdev_lock_and_get_active_state(sd);
> > +
> >  	if (enable) {
> >  		ret = pm_runtime_resume_and_get(imx290->dev);
> >  		if (ret < 0)
> > -			goto unlock_and_return;
> > +			goto unlock;
> > 
> > -		ret = imx290_start_streaming(imx290);
> > +		ret = imx290_start_streaming(imx290, state);
> >  		if (ret) {
> >  			dev_err(imx290->dev, "Start stream failed\n");
> >  			pm_runtime_put(imx290->dev);
> > -			goto unlock_and_return;
> > +			goto unlock;
> >  		}
> >  	} else {
> >  		imx290_stop_streaming(imx290);
> >  		pm_runtime_put(imx290->dev);
> >  	}
> > 
> > -unlock_and_return:
> > -
> > +unlock:
> > +	v4l2_subdev_unlock_state(state);
> >  	return ret;
> >  }
> > 
> > -static struct v4l2_mbus_framefmt *
> > -imx290_get_pad_format(struct imx290 *imx290, struct v4l2_subdev_state
> > *state, -		      u32 which)
> > -{
> > -	if (which == V4L2_SUBDEV_FORMAT_ACTIVE)
> > -		return &imx290->current_format;
> > -	else
> > -		return v4l2_subdev_get_try_format(&imx290->sd, state, 0);
> > -}
> > -
> >  static int imx290_enum_mbus_code(struct v4l2_subdev *sd,
> >  				 struct v4l2_subdev_state *sd_state,
> >  				 struct v4l2_subdev_mbus_code_enum *code)
> > @@ -858,23 +852,6 @@ static int imx290_enum_frame_size(struct v4l2_subdev
> > *sd, return 0;
> >  }
> > 
> > -static int imx290_get_fmt(struct v4l2_subdev *sd,
> > -			  struct v4l2_subdev_state *sd_state,
> > -			  struct v4l2_subdev_format *fmt)
> > -{
> > -	struct imx290 *imx290 = to_imx290(sd);
> > -	struct v4l2_mbus_framefmt *framefmt;
> > -
> > -	mutex_lock(&imx290->lock);
> > -
> > -	framefmt = imx290_get_pad_format(imx290, sd_state, fmt->which);
> > -	fmt->format = *framefmt;
> > -
> > -	mutex_unlock(&imx290->lock);
> > -
> > -	return 0;
> > -}
> > -
> >  static int imx290_set_fmt(struct v4l2_subdev *sd,
> >  			  struct v4l2_subdev_state *sd_state,
> >  			  struct v4l2_subdev_format *fmt)
> > @@ -884,8 +861,6 @@ static int imx290_set_fmt(struct v4l2_subdev *sd,
> >  	struct v4l2_mbus_framefmt *format;
> >  	unsigned int i;
> > 
> > -	mutex_lock(&imx290->lock);
> > -
> >  	mode = v4l2_find_nearest_size(imx290_modes_ptr(imx290),
> >  				      imx290_modes_num(imx290), width, height,
> >  				      fmt->format.width, fmt-
> >format.height);
> > @@ -903,7 +878,7 @@ static int imx290_set_fmt(struct v4l2_subdev *sd,
> >  	fmt->format.code = imx290_formats[i].code;
> >  	fmt->format.field = V4L2_FIELD_NONE;
> > 
> > -	format = imx290_get_pad_format(imx290, sd_state, fmt->which);
> > +	format = v4l2_subdev_get_pad_format(sd, sd_state, 0);
> > 
> >  	if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE) {
> >  		imx290->current_mode = mode;
> > @@ -914,8 +889,6 @@ static int imx290_set_fmt(struct v4l2_subdev *sd,
> > 
> >  	*format = fmt->format;
> > 
> > -	mutex_unlock(&imx290->lock);
> > -
> >  	return 0;
> >  }
> > 
> > @@ -923,14 +896,11 @@ static int imx290_get_selection(struct v4l2_subdev
> > *sd, struct v4l2_subdev_state *sd_state,
> >  				struct v4l2_subdev_selection *sel)
> >  {
> > -	struct imx290 *imx290 = to_imx290(sd);
> >  	struct v4l2_mbus_framefmt *format;
> > 
> >  	switch (sel->target) {
> >  	case V4L2_SEL_TGT_CROP: {
> > -		format = imx290_get_pad_format(imx290, sd_state, sel->which);
> > -
> > -		mutex_lock(&imx290->lock);
> > +		format = v4l2_subdev_get_pad_format(sd, sd_state, 0);
> > 
> >  		sel->r.top = IMX920_PIXEL_ARRAY_MARGIN_TOP
> >  			   + (IMX290_PIXEL_ARRAY_RECORDING_HEIGHT - format->height) / 2;
> > @@ -939,7 +909,6 @@ static int imx290_get_selection(struct v4l2_subdev *sd,
> >  		sel->r.width = format->width;
> >  		sel->r.height = format->height;
> > 
> > -		mutex_unlock(&imx290->lock);
> >  		return 0;
> >  	}
> > 
> > @@ -968,11 +937,13 @@ static int imx290_get_selection(struct v4l2_subdev
> > *sd, static int imx290_entity_init_cfg(struct v4l2_subdev *subdev,
> >  				  struct v4l2_subdev_state *sd_state)
> >  {
> > -	struct v4l2_subdev_format fmt = { 0 };
> > -
> > -	fmt.which = sd_state ? V4L2_SUBDEV_FORMAT_TRY : V4L2_SUBDEV_FORMAT_ACTIVE;
> > -	fmt.format.width = 1920;
> > -	fmt.format.height = 1080;
> > +	struct v4l2_subdev_format fmt = {
> > +		.which = V4L2_SUBDEV_FORMAT_TRY,
> > +		.format = {
> > +			.width = 1920,
> > +			.height = 1080,
> > +		},
> > +	};
> > 
> >  	imx290_set_fmt(subdev, sd_state, &fmt);
> > 
> > @@ -987,7 +958,7 @@ static const struct v4l2_subdev_pad_ops imx290_pad_ops =
> > { .init_cfg = imx290_entity_init_cfg,
> >  	.enum_mbus_code = imx290_enum_mbus_code,
> >  	.enum_frame_size = imx290_enum_frame_size,
> > -	.get_fmt = imx290_get_fmt,
> > +	.get_fmt = v4l2_subdev_get_fmt,
> >  	.set_fmt = imx290_set_fmt,
> >  	.get_selection = imx290_get_selection,
> >  };
> > @@ -1004,20 +975,12 @@ static const struct media_entity_operations
> > imx290_subdev_entity_ops = { static int imx290_subdev_init(struct imx290
> > *imx290)
> >  {
> >  	struct i2c_client *client = to_i2c_client(imx290->dev);
> > +	const struct v4l2_mbus_framefmt *format;
> > +	struct v4l2_subdev_state *state;
> >  	int ret;
> > 
> > -	/*
> > -	 * Initialize the frame format. In particular, imx290->current_mode
> > -	 * and imx290->bpp are set to defaults: imx290_calc_pixel_rate() call
> > -	 * below relies on these fields.
> > -	 */
> > -	imx290_entity_init_cfg(&imx290->sd, NULL);
> > -
> > -	ret = imx290_ctrl_init(imx290);
> > -	if (ret < 0) {
> > -		dev_err(imx290->dev, "Control initialization error %d\n", ret);
> > -		return ret;
> > -	}
> > +	imx290->current_mode = &imx290_modes_ptr(imx290)[0];
> > +	imx290->bpp = imx290_formats[0].bpp;
> > 
> >  	v4l2_i2c_subdev_init(&imx290->sd, client, &imx290_subdev_ops);
> >  	imx290->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> > @@ -1032,6 +995,22 @@ static int imx290_subdev_init(struct imx290 *imx290)
> >  		return ret;
> >  	}
> > 
> > +	ret = imx290_ctrl_init(imx290);
> > +	if (ret < 0) {
> > +		dev_err(imx290->dev, "Control initialization error %d\n", ret);
> > +		media_entity_cleanup(&imx290->sd.entity);
> > +		return ret;
> > +	}
> > +
> > +	imx290->sd.state_lock = imx290->ctrls.lock;
> > +
> > +	v4l2_subdev_init_finalize(&imx290->sd);
> > +
> > +	state = v4l2_subdev_lock_and_get_active_state(&imx290->sd);
> > +	format = v4l2_subdev_get_pad_format(&imx290->sd, state, 0);
> > +	imx290_ctrl_update(imx290, format, imx290->current_mode);
> > +	v4l2_subdev_unlock_state(state);
> 
> Do you need to check for state == NULL here?

No, v4l2_subdev_lock_and_get_active_state() can only return NULL if the
subdev driver doesn't have an active state, and
v4l2_subdev_init_finalize() guarantees it has one.

> > +
> >  	return 0;
> >  }
> > 
> > @@ -1268,12 +1247,10 @@ static int imx290_probe(struct i2c_client *client)
> >  	if (ret)
> >  		return ret;
> > 
> > -	mutex_init(&imx290->lock);
> > -
> >  	/* Initialize and register subdev. */
> >  	ret = imx290_subdev_init(imx290);
> >  	if (ret)
> > -		goto err_mutex;
> > +		return ret;
> > 
> >  	ret = v4l2_async_register_subdev(&imx290->sd);
> >  	if (ret < 0) {
> > @@ -1305,8 +1282,6 @@ static int imx290_probe(struct i2c_client *client)
> > 
> >  err_subdev:
> >  	imx290_subdev_cleanup(imx290);
> > -err_mutex:
> > -	mutex_destroy(&imx290->lock);
> > 
> >  	return ret;
> >  }
> > @@ -1319,8 +1294,6 @@ static void imx290_remove(struct i2c_client *client)
> >  	v4l2_async_unregister_subdev(sd);
> >  	imx290_subdev_cleanup(imx290);
> > 
> > -	mutex_destroy(&imx290->lock);
> > -
> >  	pm_runtime_disable(imx290->dev);
> >  	if (!pm_runtime_status_suspended(imx290->dev))
> >  		imx290_power_off(imx290->dev);

-- 
Regards,

Laurent Pinchart