linux-kernel - [PATCH] leds: lm3601x: Calculate max_brightness and brightness properly

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Message-ID: <20240704190157.712590-1-zenghuchen@google.com>
Date: Thu,  4 Jul 2024 15:01:57 -0400
From: Jack Chen <zenghuchen@...gle.com>
To: Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>
Cc: Mark Brown <broonie@...nel.org>, Vadim Pasternak <vadimp@...dia.com>, 
	Randy Dunlap <rdunlap@...radead.org>, Jack Chen <zenghuchen@...gle.com>, 
	linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: [PATCH] leds: lm3601x: Calculate max_brightness and brightness properly

The torch_current_max should be checked not exceeding the upper bound.
If it does, throw a warning message and set to LM3601X_MAX_TORCH_I_UA.

LM3601x torch brigthness register (LM3601X_LED_TORCH_REG) takes 0 as the
minimum output (2.4 mA). However, 0 of led_brightness means LED_OFF.
Adding a -1 offset to brightness before writing to brightness
register, so when users write minimum brightness (1), it sets lm3601x
output the minimum.

Signed-off-by: Jack Chen <zenghuchen@...gle.com>
---
 drivers/leds/flash/leds-lm3601x.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/flash/leds-lm3601x.c b/drivers/leds/flash/leds-lm3601x.c
index 7e93c447fec5..fc4df904ea90 100644
--- a/drivers/leds/flash/leds-lm3601x.c
+++ b/drivers/leds/flash/leds-lm3601x.c
@@ -190,7 +190,7 @@ static int lm3601x_brightness_set(struct led_classdev *cdev,
 		goto out;
 	}
 
-	ret = regmap_write(led->regmap, LM3601X_LED_TORCH_REG, brightness);
+	ret = regmap_write(led->regmap, LM3601X_LED_TORCH_REG, brightness - 1);
 	if (ret < 0)
 		goto out;
 
@@ -341,8 +341,9 @@ static int lm3601x_register_leds(struct lm3601x_led *led,
 
 	led_cdev = &led->fled_cdev.led_cdev;
 	led_cdev->brightness_set_blocking = lm3601x_brightness_set;
-	led_cdev->max_brightness = DIV_ROUND_UP(led->torch_current_max,
-						LM3601X_TORCH_REG_DIV);
+	led_cdev->max_brightness = DIV_ROUND_UP(
+			led->torch_current_max - LM3601X_MIN_TORCH_I_UA + 1,
+			LM3601X_TORCH_REG_DIV);
 	led_cdev->flags |= LED_DEV_CAP_FLASH;
 
 	init_data.fwnode = fwnode;
@@ -386,6 +387,14 @@ static int lm3601x_parse_node(struct lm3601x_led *led,
 		goto out_err;
 	}
 
+	if (led->torch_current_max > LM3601X_MAX_TORCH_I_UA) {
+		dev_warn(&led->client->dev,
+			 "led-max-microamp cannot be higher than %d\n",
+			 LM3601X_MAX_TORCH_I_UA);
+		led->torch_current_max = LM3601X_MAX_TORCH_I_UA;
+	}
+
+
 	ret = fwnode_property_read_u32(child, "flash-max-microamp",
 				&led->flash_current_max);
 	if (ret) {
-- 
2.45.2.803.g4e1b14247a-goog