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From:   Dmitry Rokosov <ddrokosov@salutedevices.com>
To:     <lee@kernel.org>, <pavel@ucw.cz>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <conor+dt@kernel.org>,
        <andy.shevchenko@gmail.com>
CC:     <kernel@sberdevices.ru>, <rockosov@gmail.com>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-leds@vger.kernel.org>,
        George Stark <gnstark@salutedevices.com>,
        Dmitry Rokosov <ddrokosov@salutedevices.com>
Subject: [PATCH v2 08/11] leds: aw200xx: improve autodim calculation method
Date:   Wed, 18 Oct 2023 21:29:40 +0300
Message-ID: <20231018182943.18700-9-ddrokosov@salutedevices.com>
In-Reply-To: <20231018182943.18700-1-ddrokosov@salutedevices.com>
References: <20231018182943.18700-1-ddrokosov@salutedevices.com>
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From: George Stark <gnstark@salutedevices.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@salutedevices.com>
Signed-off-by: Dmitry Rokosov <ddrokosov@salutedevices.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 ad4bfb9f0938..7b8802bd9497 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