On 03/29/2016 10:42 PM, Heiner Kallweit wrote:
Am 29.03.2016 um 12:05 schrieb Pavel Machek:
On Tue 2016-03-01 22:36:12, 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 <hkallweit1@xxxxxxxxx>
---
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
v5:
- don't ignore led_cdev->brightness_get silently if LED_DEV_CAP_RGB
is set but warn
---
drivers/leds/led-class.c | 7 +++++++
drivers/leds/led-rgb-core.c | 36 ++++++++++++++++++++++++++++++++++++
include/linux/leds.h | 8 ++++++++
3 files changed, 51 insertions(+)
diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 8a3748a..a4b144e 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -193,6 +193,13 @@ int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
char name[64];
int ret;
+ /*
+ * 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
+ */
+ WARN_ON(led_cdev->flags & LED_DEV_CAP_RGB && led_cdev->brightness_get);
+
Backtrace is useless here, you may want to add some ()s and you don't
really want user to be causing messages in syslog this easily.
I agree that the backtrace doesn't provide a benefit here.
I requested it to provide a verbose notification for a LED RGB class
driver developer, in case they try to implement a brightness_get
op, which would be harmful in case of HSV interface for RGB LEDs.
However I don't see how a user could create syslog entries.
The warn condition can be true only for drivers implementing the RGB extension
in a not supported way (by setting flag LED_DEV_CAP_RGB and implementing
brightness_get).
Pavel
--
Best regards,
Jacek Anaszewski
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