Re: [PATCH] media: i2c: imx219: Use dev_err_probe on probe

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

Hi Umang,

On Thu, Mar 14, 2024 at 06:51:04PM +0530, Umang Jain wrote:
> On 11/03/24 5:05 pm, Tommaso Merciai wrote:
> > On Mon, Mar 11, 2024 at 02:30:42PM +0530, Umang Jain wrote:
> >> Drop dev_err() and use the dev_err_probe() helper on probe path.
> >>
> >> No functional changes intended.
> >>
> >> Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
> >> ---
> >>   drivers/media/i2c/imx219.c | 64 +++++++++++++++++++-------------------
> >>   1 file changed, 32 insertions(+), 32 deletions(-)
> >>
> >> diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> >> index e17ef2e9d9d0..acd27e2ef849 100644
> >> --- a/drivers/media/i2c/imx219.c
> >> +++ b/drivers/media/i2c/imx219.c
> >> @@ -551,8 +551,9 @@ static int imx219_init_controls(struct imx219 *imx219)
> >>   
> >>   	if (ctrl_hdlr->error) {
> >>   		ret = ctrl_hdlr->error;
> >> -		dev_err(&client->dev, "%s control init failed (%d)\n",
> >> -			__func__, ret);
> >> +		dev_err_probe(&client->dev, ret,
> >> +			      "%s control init failed\n",
> >> +			      __func__);

ctrl_hdlr->error can never be -EPROBE_DEFER, is dev_err_probe() really
useful here ?

> >>   		goto error;
> >>   	}
> >>   
> >> @@ -1025,15 +1026,15 @@ static int imx219_identify_module(struct imx219 *imx219)
> >>   
> >>   	ret = cci_read(imx219->regmap, IMX219_REG_CHIP_ID, &val, NULL);
> >>   	if (ret) {
> >> -		dev_err(&client->dev, "failed to read chip id %x\n",
> >> -			IMX219_CHIP_ID);
> >> -		return ret;
> >> +		return dev_err_probe(&client->dev, ret,
> >> +				     "failed to read chip id %x\n",
> >> +				     IMX219_CHIP_ID);
> >>   	}
> >
> > I think you can remove also here the curve brakets we don't need that
> > anymore.
> 
> I think multi-line single statement like this one, is better with { ... 
> } and is actually preferred?
> 
> I actually got a review-comment about this long ago(don't remember when) 
> in a non-related, kernel patch series.
> 
> I'll leaving this upto maintainers probably

I think the preferred coding style in the media subsystem is to leave
the curly brackets out for all single statements, even if the statement
spans multiple lines.

> >>   
> >>   	if (val != IMX219_CHIP_ID) {
> >> -		dev_err(&client->dev, "chip id mismatch: %x!=%llx\n",
> >> -			IMX219_CHIP_ID, val);
> >> -		return -EIO;
> >> +		return dev_err_probe(&client->dev, -EIO,
> >> +				     "chip id mismatch: %x!=%llx\n",
> >> +				     IMX219_CHIP_ID, val);
> >>   	}
> >
> > ditto
> >
> >>   
> >>   	return 0;
> >> @@ -1048,35 +1049,36 @@ static int imx219_check_hwcfg(struct device *dev, struct imx219 *imx219)
> >>   	int ret = -EINVAL;
> >>   
> >>   	endpoint = fwnode_graph_get_next_endpoint(dev_fwnode(dev), NULL);
> >> -	if (!endpoint) {
> >> -		dev_err(dev, "endpoint node not found\n");
> >> -		return -EINVAL;
> >> -	}
> >> +	if (!endpoint)
> >> +		return dev_err_probe(dev, -EINVAL, "endpoint node not found\n");

Same here, what's the advantage of using dev_err_probe() when you
hardcode the error value to something different than -EPROBE_DEFER ?
Same below.

> >>   
> >>   	if (v4l2_fwnode_endpoint_alloc_parse(endpoint, &ep_cfg)) {
> >> -		dev_err(dev, "could not parse endpoint\n");
> >> +		dev_err_probe(dev, -EINVAL, "could not parse endpoint\n");

This I like even less. -EINVAL is meaningless here, it's not even
guaranteed to be the error code that the function will return.

> >>   		goto error_out;
> >>   	}
> >>   
> >>   	/* Check the number of MIPI CSI2 data lanes */
> >>   	if (ep_cfg.bus.mipi_csi2.num_data_lanes != 2 &&
> >>   	    ep_cfg.bus.mipi_csi2.num_data_lanes != 4) {
> >> -		dev_err(dev, "only 2 or 4 data lanes are currently supported\n");
> >> +		dev_err_probe(dev, -EINVAL,
> >> +			      "only 2 or 4 data lanes are currently supported\n");
> >>   		goto error_out;
> >>   	}
> >>   	imx219->lanes = ep_cfg.bus.mipi_csi2.num_data_lanes;
> >>   
> >>   	/* Check the link frequency set in device tree */
> >>   	if (!ep_cfg.nr_of_link_frequencies) {
> >> -		dev_err(dev, "link-frequency property not found in DT\n");
> >> +		dev_err_probe(dev, -EINVAL,
> >> +			      "link-frequency property not found in DT\n");
> >>   		goto error_out;
> >>   	}
> >>   
> >>   	if (ep_cfg.nr_of_link_frequencies != 1 ||
> >>   	   (ep_cfg.link_frequencies[0] != ((imx219->lanes == 2) ?
> >>   	    IMX219_DEFAULT_LINK_FREQ : IMX219_DEFAULT_LINK_FREQ_4LANE))) {
> >> -		dev_err(dev, "Link frequency not supported: %lld\n",
> >> -			ep_cfg.link_frequencies[0]);
> >> +		dev_err_probe(dev, -EINVAL,
> >> +			      "Link frequency not supported: %lld\n",
> >> +			      ep_cfg.link_frequencies[0]);
> >>   		goto error_out;
> >>   	}
> >>   
> >> @@ -1108,30 +1110,27 @@ static int imx219_probe(struct i2c_client *client)
> >>   
> >>   	imx219->regmap = devm_cci_regmap_init_i2c(client, 16);
> >>   	if (IS_ERR(imx219->regmap)) {
> >> -		ret = PTR_ERR(imx219->regmap);
> >> -		dev_err(dev, "failed to initialize CCI: %d\n", ret);
> >> -		return ret;
> >> +		return dev_err_probe(dev, PTR_ERR(imx219->regmap),
> >> +				     "failed to initialize CCI\n");
> >>   	}
> >
> > ditto
> >
> >>   
> >>   	/* Get system clock (xclk) */
> >>   	imx219->xclk = devm_clk_get(dev, NULL);
> >>   	if (IS_ERR(imx219->xclk)) {
> >> -		dev_err(dev, "failed to get xclk\n");
> >> -		return PTR_ERR(imx219->xclk);
> >> +		return dev_err_probe(dev, PTR_ERR(imx219->xclk),
> >> +				     "failed to get xclk\n");

This change makes sense, the clock provider may not have probed yet
(even if it's quite unlikely).

> >>   	}
> >
> > ditto
> >
> >>   
> >>   	imx219->xclk_freq = clk_get_rate(imx219->xclk);
> >>   	if (imx219->xclk_freq != IMX219_XCLK_FREQ) {
> >> -		dev_err(dev, "xclk frequency not supported: %d Hz\n",
> >> -			imx219->xclk_freq);
> >> -		return -EINVAL;
> >> +		return dev_err_probe(dev, -EINVAL,
> >> +				     "xclk frequency not supported: %d Hz\n",
> >> +				     imx219->xclk_freq);
> >>   	}
> >
> > ditto
> >
> >>   
> >>   	ret = imx219_get_regulators(imx219);
> >> -	if (ret) {
> >> -		dev_err(dev, "failed to get regulators\n");
> >> -		return ret;
> >> -	}
> >> +	if (ret)
> >> +		return dev_err_probe(dev, ret, "failed to get regulators\n");

Same here.

> >>   
> >>   	/* Request optional enable pin */
> >>   	imx219->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> >> @@ -1183,20 +1182,21 @@ static int imx219_probe(struct i2c_client *client)
> >>   
> >>   	ret = media_entity_pads_init(&imx219->sd.entity, 1, &imx219->pad);
> >>   	if (ret) {
> >> -		dev_err(dev, "failed to init entity pads: %d\n", ret);
> >> +		dev_err_probe(dev, ret, "failed to init entity pads\n");
> >>   		goto error_handler_free;
> >>   	}
> >>   
> >>   	imx219->sd.state_lock = imx219->ctrl_handler.lock;
> >>   	ret = v4l2_subdev_init_finalize(&imx219->sd);
> >>   	if (ret < 0) {
> >> -		dev_err(dev, "subdev init error: %d\n", ret);
> >> +		dev_err_probe(dev, ret, "subdev init error\n");
> >>   		goto error_media_entity;
> >>   	}
> >>   
> >>   	ret = v4l2_async_register_subdev_sensor(&imx219->sd);
> >>   	if (ret < 0) {
> >> -		dev_err(dev, "failed to register sensor sub-device: %d\n", ret);
> >> +		dev_err_probe(dev, ret,
> >> +			      "failed to register sensor sub-device\n");
> >>   		goto error_subdev_cleanup;
> >>   	}
> >>   

-- 
Regards,

Laurent Pinchart