linux-kernel - [PATCH v4 08/11] leds: aw200xx: improve autodim calculation method

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Message-ID: <20231121202835.28152-9-ddrokosov@salutedevices.com>
Date:   Tue, 21 Nov 2023 23:28:32 +0300
From:   Dmitry Rokosov <ddrokosov@...utedevices.com>
To:     <lee@...nel.org>, <pavel@....cz>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <andy.shevchenko@...il.com>
CC:     <kernel@...rdevices.ru>, <rockosov@...il.com>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-leds@...r.kernel.org>,
        George Stark <gnstark@...utedevices.com>,
        Dmitry Rokosov <ddrokosov@...utedevices.com>
Subject: [PATCH v4 08/11] leds: aw200xx: improve autodim calculation method

From: George Stark <gnstark@...utedevices.com>

It is highly recommended to leverage the DIV_ROUND_UP() function as a
more refined and mathematically precise alternative to employing a
coarse division method.

Signed-off-by: George Stark <gnstark@...utedevices.com>
Signed-off-by: Dmitry Rokosov <ddrokosov@...utedevices.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
---
 drivers/leds/leds-aw200xx.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/leds/leds-aw200xx.c b/drivers/leds/leds-aw200xx.c
index 4c83d4979cf5..c48aa11fd411 100644
--- a/drivers/leds/leds-aw200xx.c
+++ b/drivers/leds/leds-aw200xx.c
@@ -87,6 +87,8 @@
 #define AW200XX_REG_DIM(x, columns) \
 	AW200XX_REG(AW200XX_PAGE4, AW200XX_LED2REG(x, columns) * 2)
 #define AW200XX_REG_DIM2FADE(x) ((x) + 1)
+#define AW200XX_REG_FADE2DIM(fade) \
+	DIV_ROUND_UP((fade) * AW200XX_DIM_MAX, AW200XX_FADE_MAX)
 
 /*
  * Duty ratio of display scan (see p.15 of datasheet for formula):
@@ -195,9 +197,7 @@ static int aw200xx_brightness_set(struct led_classdev *cdev,
 
 	dim = led->dim;
 	if (dim < 0)
-		dim = max_t(int,
-			    brightness / (AW200XX_FADE_MAX / AW200XX_DIM_MAX),
-			    1);
+		dim = AW200XX_REG_FADE2DIM(brightness);
 
 	ret = regmap_write(chip->regmap, reg, dim);
 	if (ret)
@@ -460,6 +460,7 @@ static int aw200xx_probe_fw(struct device *dev, struct aw200xx *chip)
 		led->num = source;
 		led->chip = chip;
 		led->cdev.brightness_set_blocking = aw200xx_brightness_set;
+		led->cdev.max_brightness = AW200XX_FADE_MAX;
 		led->cdev.groups = dim_groups;
 		init_data.fwnode = child;
 
-- 
2.36.0