From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jacek Anaszewski Subject: Re: [PATCH v4 4/4] leds: core: add support for HSV to RGB conversion Date: Mon, 29 Feb 2016 17:13:03 +0100 Message-ID: <56D46E0F.5080806@samsung.com> References: <56CF7D6D.50001@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.w1.samsung.com ([210.118.77.12]:60503 "EHLO mailout2.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755548AbcB2QNI (ORCPT ); Mon, 29 Feb 2016 11:13:08 -0500 Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout2.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0O3B008TRH1SXR50@mailout2.w1.samsung.com> for linux-leds@vger.kernel.org; Mon, 29 Feb 2016 16:13:04 +0000 (GMT) In-reply-to: <56CF7D6D.50001@gmail.com> Sender: linux-leds-owner@vger.kernel.org List-Id: linux-leds@vger.kernel.org To: Heiner Kallweit Cc: linux-leds@vger.kernel.org Hi Heiner, On 02/25/2016 11:17 PM, Heiner Kallweit wrote: > Export a function to convert HSV color values to RGB. > It's intended to be called by drivers for RGB LEDs. > > Signed-off-by: Heiner Kallweit > --- > v2: > - move hsv -> rgb conversion to separate file > - remove flag LED_DEV_CAP_RGB > v3: > - call led_hsv_to_rgb only if LED_DEV_CAP_HSV is set > This is needed in cases when we have monochrome and color LEDs > as well in a system. > v4: > - Export led_hsv_to_rgb and let the device driver call it instead > of doing the conversion in the core > --- > drivers/leds/led-core.c | 7 ++++++- > drivers/leds/led-rgb-core.c | 36 ++++++++++++++++++++++++++++++++++++ > include/linux/leds.h | 8 ++++++++ > 3 files changed, 50 insertions(+), 1 deletion(-) > > diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c > index e75b0c8..e3ee971 100644 > --- a/drivers/leds/led-core.c > +++ b/drivers/leds/led-core.c > @@ -295,7 +295,12 @@ int led_update_brightness(struct led_classdev *led_cdev) > { > int ret = 0; > > - if (led_cdev->brightness_get) { > + /* > + * for now reading back the color is not supported as multiple > + * HSV -> RGB -> HSV conversions may distort the color due to > + * rounding issues in the conversion algorithm > + */ This is very unpleasant. Is it really not feasible to work this around? > + if (led_cdev->brightness_get && !(led_cdev->flags & LED_DEV_CAP_HSV)) { > ret = led_cdev->brightness_get(led_cdev); > if (ret >= 0) { > led_cdev->brightness = ret; > diff --git a/drivers/leds/led-rgb-core.c b/drivers/leds/led-rgb-core.c > index b81daeb..4691795 100644 > --- a/drivers/leds/led-rgb-core.c > +++ b/drivers/leds/led-rgb-core.c > @@ -40,3 +40,39 @@ enum led_brightness led_confine_brightness(struct led_classdev *led_cdev, > return brightness | > min(value & LED_BRIGHTNESS_MASK, led_cdev->max_brightness); > } > + > +enum led_brightness led_hsv_to_rgb(enum led_brightness hsv) > +{ > + int h = min_t(int, (hsv >> 16) & 0xff, 251); > + int s = (hsv >> 8) & 0xff; > + int v = hsv & 0xff; > + int f, p, q, t, r, g, b; > + > + if (!v) > + return 0; > + if (!s) > + return (v << 16) + (v << 8) + v; > + > + f = DIV_ROUND_CLOSEST((h % 42) * 255, 42); > + p = v - DIV_ROUND_CLOSEST(s * v, 255); > + q = v - DIV_ROUND_CLOSEST(f * s * v, 255 * 255); > + t = v - DIV_ROUND_CLOSEST((255 - f) * s * v, 255 * 255); > + > + switch (h / 42) { > + case 0: > + r = v; g = t; b = p; break; > + case 1: > + r = q; g = v; b = p; break; > + case 2: > + r = p; g = v; b = t; break; > + case 3: > + r = p; g = q; b = v; break; > + case 4: > + r = t; g = p; b = v; break; > + case 5: > + r = v; g = p; b = q; break; > + } > + > + return (r << 16) + (g << 8) + b; > +} > +EXPORT_SYMBOL_GPL(led_hsv_to_rgb); > diff --git a/include/linux/leds.h b/include/linux/leds.h > index 1e98b2e..27725c6 100644 > --- a/include/linux/leds.h > +++ b/include/linux/leds.h > @@ -226,6 +226,14 @@ static inline bool led_sysfs_is_disabled(struct led_classdev *led_cdev) > return led_cdev->flags & LED_SYSFS_DISABLE; > } > > +/** > + * led_hsv_to_rgb - convert a hsv color value to rgb color model > + * @hsv: the hsv value to convert > + * > + * Returns: the resulting rgb value > + */ > +enum led_brightness led_hsv_to_rgb(enum led_brightness hsv); > + > /* > * LED Triggers > */ > -- Best regards, Jacek Anaszewski