Re: [PATCH v2 2/2] leds: add sgm3140 driver

Luca Weiss
2020-04-04T09:36:49Z

Hi Dan,

On Freitag, 3. April 2020 19:31:52 CEST Dan Murphy wrote:
> Luca
>
> On 3/30/20 2:47 PM, Luca Weiss wrote:
> > Add a driver for the SGMICRO SGM3140 Buck/Boost Charge Pump LED driver.
> >
> > This device is controlled by two GPIO pins, one for enabling and the
> > second one for switching between torch and flash mode.
> >
> > Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
> > ---
> > Changes since v1:
> > - Add vin-supply (keep track of 'enabled' state for that)
> > - Wrap lines
> > - static const -ify some structs and methods
> > - use strscpy instead of strlcpy
> > - remove u32 cast by adding 'U' suffix to constants
> > - rebase on linux-next
> >
> > drivers/leds/Kconfig | 9 +
> > drivers/leds/Makefile | 1 +
> > drivers/leds/leds-sgm3140.c | 317 ++++++++++++++++++++++++++++++++++++
> > 3 files changed, 327 insertions(+)
> > create mode 100644 drivers/leds/leds-sgm3140.c
> >
-snip-
> > +
> > + priv->vin_regulator = devm_regulator_get(&pdev->dev, "vin");
> > + ret = PTR_ERR_OR_ZERO(priv->vin_regulator);
> > + if (ret) {
> > + if (ret != -EPROBE_DEFER)
> > + dev_err(&pdev->dev,
> > + "Failed to request regulator:
%d\n", ret);
> > + return ret;
>
> This regulator is optional so why would you return here? You should
> only return if -EPROBE_DEFER.

If the regulator is not specified in the dts, then a dummy regulator will be
used:

[ 1.027114] sgm3140 sgm3140: sgm3140 supply vin not found, using dummy
regulator

So this code will only be called if something really failed (or was defered)

>
> > + }
> > +
> > + child_node = of_get_next_available_child(pdev->dev.of_node, NULL);
>
> Maybe this should be the first check before doing all the processing to
> make sure that the DT is not
>
> malformed.

If e.g. the devm_gpiod_get calls fail (because the gpios weren't declared in
the dts) then the dt is also "malformed" which isn't as different as the
subnode being missing imo. I don't think it matters much here. And this way I
don't have to care about calling of_node_put in case of an error for the
statements above.

>
> > + if (!child_node) {
> > + dev_err(&pdev->dev,
> > + "No DT child node found for connected LED.
\n");
> > + return -EINVAL;
> > + }
> > +
> > + ret = of_property_read_u32(child_node, "flash-max-timeout-us",
> > + &priv->max_timeout);
> > + if (ret) {
> > + priv->max_timeout = FLASH_MAX_TIMEOUT_DEFAULT;
> > + dev_warn(&pdev->dev,
> > + "flash-max-timeout-us DT property
missing\n");
> > + }
> > +
> > + /*
> > + * Set default timeout to FLASH_DEFAULT_TIMEOUT except if
max_timeout
> > + * from DT is lower.
> > + */
> > + priv->timeout = min(priv->max_timeout, FLASH_TIMEOUT_DEFAULT);
> > +
> > + timer_setup(&priv->powerdown_timer, sgm3140_powerdown_timer, 0);
> > +
> > + fled_cdev = &priv->fled_cdev;
> > + led_cdev = &fled_cdev->led_cdev;
> > +
> > + fled_cdev->ops = &sgm3140_flash_ops;
> > +
> > + led_cdev->brightness_set_blocking = sgm3140_brightness_set;
> > + led_cdev->max_brightness = LED_ON;
> > + led_cdev->flags |= LED_DEV_CAP_FLASH;
> > +
> > + sgm3140_init_flash_timeout(priv);
> > +
> > + init_data.fwnode = of_fwnode_handle(child_node);
> > +
> > + platform_set_drvdata(pdev, priv);
> > +
> > + /* Register in the LED subsystem */
> > + ret = devm_led_classdev_flash_register_ext(&pdev->dev,
> > +
fled_cdev, &init_data);
> > + if (ret) {
> > + dev_err(&pdev->dev, "Failed to register flash device:
%d\n",
> > + ret);
> > + goto err;
> > + }
> > +
> > + sgm3140_init_v4l2_flash_config(priv, &v4l2_sd_cfg);
> > +
> > + /* Create V4L2 Flash subdev */
> > + priv->v4l2_flash = v4l2_flash_init(&pdev->dev,
> > +
of_fwnode_handle(child_node),
> > + fled_cdev, NULL,
> > + &v4l2_sd_cfg);
> > + if (IS_ERR(priv->v4l2_flash)) {
> > + ret = PTR_ERR(priv->v4l2_flash);
> > + goto err;
>
> Not sure why this is here you are not in a for loop and this will fall
> through anyway to the err label.
>

I kept the goto in, in case more code is added below that statement so the
author doesn't forget that this error needs to be handled.
If wanted I can remove it of course.

> > + }
> > +
> > +err:
> > + of_node_put(child_node);
> > + return ret;
> > +}
> > +
>
> Dan

Regards
Luca