linux-kernel - [PATCH v3 2/2] led: led-class: Read max-brightness from devicetree

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Message-ID: <20230703130313.548519-3-astrid.rost@axis.com>
Date:   Mon, 3 Jul 2023 15:03:13 +0200
From:   Astrid Rost <astrid.rost@...s.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh@...nel.org>,
        "Jacek Anaszewski" <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, "Lee Jones" <lee@...nel.org>
CC:     <kernel@...s.com>, Astrid Rost <astrid.rost@...s.com>,
        <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 2/2] led: led-class: Read max-brightness from devicetree

Normally, the maximum brightness is determined by the hardware, and this
property is not required. This property is used to set a software limit.
It could happen that an LED is made so bright that it gets damaged or
causes damage due to restrictions in a specific system, such as mounting
conditions.
Note that this flag is mainly used for PWM-LEDs, where it is not possible
to map brightness to current. Drivers for other controllers should use
led-max-microamp.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Signed-off-by: Astrid Rost <astrid.rost@...s.com>
---
 drivers/leds/led-class.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 9255bc11f99d..ce652abf9336 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -457,6 +457,10 @@ int led_classdev_register_ext(struct device *parent,
 			if (fwnode_property_present(init_data->fwnode,
 						    "retain-state-shutdown"))
 				led_cdev->flags |= LED_RETAIN_AT_SHUTDOWN;
+
+			fwnode_property_read_u32(init_data->fwnode,
+				"max-brightness",
+				&led_cdev->max_brightness);
 		}
 	} else {
 		proposed_name = led_cdev->name;
-- 
2.30.2