| Message ID | 20230801124931.8661-1-kabel@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | leds: multicolor: Use rounded division when calculating color components | expand |
On Tue, 01 Aug 2023 14:49:31 +0200, Marek Behún wrote: > 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. > > [...] Applied, thanks! [1/1] leds: multicolor: Use rounded division when calculating color components commit: 065d099f1be58187e6629273c50b948a02b7e1bf -- Lee Jones [李琼斯]
diff --git a/drivers/leds/led-class-multicolor.c b/drivers/leds/led-class-multicolor.c index e317408583df..ec62a4811613 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; }
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> --- drivers/leds/led-class-multicolor.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)