6.4-stable review patch. If anyone has any objections, please let me know.
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From: Marek Behún kabel@kernel.org
[ Upstream commit 065d099f1be58187e6629273c50b948a02b7e1bf ]
Given channel intensity, LED brightness and max LED brightness, the multicolor LED framework helper led_mc_calc_color_components() computes the color channel brightness as
chan_brightness = brightness * chan_intensity / max_brightness
Consider the situation when (brightness, intensity, max_brightness) is for example (16, 15, 255), then chan_brightness is computed to 0 although the fractional divison would give 0.94, which should be rounded to 1.
Use DIV_ROUND_CLOSEST here for the division to give more realistic component computation:
chan_brightness = DIV_ROUND_CLOSEST(brightness * chan_intensity, max_brightness)
Fixes: 55d5d3b46b08 ("leds: multicolor: Introduce a multicolor class definition") Signed-off-by: Marek Behún kabel@kernel.org Link: https://lore.kernel.org/r/20230801124931.8661-1-kabel@kernel.org Signed-off-by: Lee Jones lee@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/leds/led-class-multicolor.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/leds/led-class-multicolor.c b/drivers/leds/led-class-multicolor.c index e317408583df9..ec62a48116135 100644 --- a/drivers/leds/led-class-multicolor.c +++ b/drivers/leds/led-class-multicolor.c @@ -6,6 +6,7 @@ #include <linux/device.h> #include <linux/init.h> #include <linux/led-class-multicolor.h> +#include <linux/math.h> #include <linux/module.h> #include <linux/slab.h> #include <linux/uaccess.h> @@ -19,9 +20,10 @@ int led_mc_calc_color_components(struct led_classdev_mc *mcled_cdev, int i;
for (i = 0; i < mcled_cdev->num_colors; i++) - mcled_cdev->subled_info[i].brightness = brightness * - mcled_cdev->subled_info[i].intensity / - led_cdev->max_brightness; + mcled_cdev->subled_info[i].brightness = + DIV_ROUND_CLOSEST(brightness * + mcled_cdev->subled_info[i].intensity, + led_cdev->max_brightness);
return 0; }