Re: [PATCH v8 5/5] backlight: add led-backlight driver

From: Jean-Jacques Hiblot
Date: Thu Oct 03 2019 - 13:30:53 EST


Sebastian,

On 03/10/2019 13:47, Sebastian Reichel wrote:
Hi,

On Thu, Oct 03, 2019 at 10:28:12AM +0200, Jean-Jacques Hiblot wrote:
From: Tomi Valkeinen <tomi.valkeinen@xxxxxx>

This patch adds a led-backlight driver (led_bl), which is similar to
pwm_bl except the driver uses a LED class driver to adjust the
brightness in the HW. Multiple LEDs can be used for a single backlight.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@xxxxxx>
Acked-by: Pavel Machek <pavel@xxxxxx>
Reviewed-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
---
Reviewed-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>

(with some suggestions below)

[...]


I suggest to restructure:

1. call led_sysfs_disable

2. use devm_add_action_or_reset() to register the
led_sysfs_enable loop

3. use devm_backlight_device_register() to register BL

4. drop the remove function

+
+ backlight_update_status(priv->bl_dev);
+
+ return 0;
+}
+
+static int led_bl_remove(struct platform_device *pdev)
+{
+ struct led_bl_data *priv = platform_get_drvdata(pdev);
+ struct backlight_device *bl = priv->bl_dev;
+ int i;
+
+ backlight_device_unregister(bl);
+
+ led_bl_power_off(priv);
+ for (i = 0; i < priv->nb_leds; i++)
+ led_sysfs_enable(priv->leds[i]);
+
+ return 0;
+}
+
+static const struct of_device_id led_bl_of_match[] = {
+ { .compatible = "led-backlight" },
+ { }
+};
+
+MODULE_DEVICE_TABLE(of, led_bl_of_match);
+
+static struct platform_driver led_bl_driver = {
+ .driver = {
+ .name = "led-backlight",
+ .of_match_table = of_match_ptr(led_bl_of_match),
You should drop of_match_ptr(). Since the driver depends on OF,
it will always simply return led_bl_of_match.

(Also after removing the OF dependency from the driver it would
either require led_bl_of_match to be marked __maybe_unused or
moving it into a #if CONFIG_OF area to avoid warnings.)

Thanks for the suggestions. I think I'll work on them as a separate thing and post them after this is merged if there are no others changes required.

JJ


-- Sebastian

+ },
+ .probe = led_bl_probe,
+ .remove = led_bl_remove,
+};
+
+module_platform_driver(led_bl_driver);
+
+MODULE_DESCRIPTION("LED based Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:led-backlight");
--
2.17.1

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