Re: [PATCH 1/3] leds: triggers: add support for RGB triggers
From: Jacek Anaszewski
Date: Tue Mar 22 2016 - 04:05:26 EST
On 03/21/2016 06:34 PM, Heiner Kallweit wrote:
Am 21.03.2016 um 16:35 schrieb Jacek Anaszewski:
On 03/19/2016 08:11 PM, Heiner Kallweit wrote:
Am 18.03.2016 um 14:10 schrieb Jacek Anaszewski:
On 03/17/2016 08:53 PM, Heiner Kallweit wrote:
Am 17.03.2016 um 14:41 schrieb Jacek Anaszewski:
Hi Heiner,
On 03/13/2016 06:14 PM, Heiner Kallweit wrote:
Add basic support for RGB triggers. Triggers with flag LED_TRIG_CAP_RGB
set are available to RGB LED devices only.
Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
drivers/leds/led-triggers.c | 15 ++++++++++++---
include/linux/leds.h | 3 +++
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 2181581..3ccf88b 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -30,6 +30,13 @@ static LIST_HEAD(trigger_list);
/* Used by LED Class */
+static inline bool led_trig_check_rgb(struct led_trigger *trig,
+ struct led_classdev *led_cdev)
+{
+ return !(trig->flags & LED_TRIG_CAP_RGB) ||
+ led_cdev->flags & LED_DEV_CAP_RGB;
+}
Could you explain what is the purpose of this function?
What actually do we want to check here?
Triggers using RGB functionality can't be used with non-RGB LED's.
This check checks for such unsupported combinations:
It returns false if the trigger uses RGB functionality but LED doesn't
support the RGB extension.
We need more meaningful name for it. Maybe led_trigger_is_supported() ?
And let's make it no-op for !CONFIG_LEDS_CLASS_RGB case.
OK, led_trigger_is_supported() is better.
Making the function a no-op in the non-RGB case would have some impact:
We'd have to make sure that all public trigger functions are a de-facto no-op
for RGB triggers (at least register / unregister). Means we would need
something like this in each public trigger function:
#if !IS_ENABLED(CONFIG_LEDS_CLASS_RGB)
if (trig->flags & LED_TRIG_CAP_RGB))
return;
#endif
I think this would add a lot of overhead and therefore IMHO it's better to
not make the check function a no-op.
Wouldn't it suffice to make the no-op returning true?
Preventing RGB trigger registration for non-RGB LED class configuration
seems to be different thing, also to be considered.
No, it's not sufficient. Let's say the RGB extension is disabled and we have a RGB trigger.
The check is a no-op now (returns always true), therefore the RGB trigger would be displayed
in the list of available triggers also for all non-RGB LED's.
If RGB trigger was made dependent on LED RGB class, then the related
Kconfig symbol would remain undefined in !CONFIG_LEDS_CLASS_RGB case.
We could maximum remove the "|| led_cdev->flags & LED_DEV_CAP_RGB" from the check if
the RGB extension is disabled. But it's open whether this minimal gain in a non-critical
code path justifies this.
ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
@@ -52,12 +59,12 @@ ssize_t led_trigger_store(struct device *dev, struct device_attribute *attr,
down_read(&triggers_list_lock);
list_for_each_entry(trig, &trigger_list, next_trig) {
if (sysfs_streq(buf, trig->name)) {
+ if (!led_trig_check_rgb(trig, led_cdev))
+ break;
Check for the case that userspace wants to set a RGB trigger for a non-RGB LED via sysfs.
down_write(&led_cdev->trigger_lock);
led_trigger_set(led_cdev, trig);
up_write(&led_cdev->trigger_lock);
-
- up_read(&triggers_list_lock);
- goto unlock;
+ break;
This seems to be an unrelated cleanup. Please submit it separately.
OK
}
}
up_read(&triggers_list_lock);
@@ -84,6 +91,8 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
len += sprintf(buf+len, "none ");
list_for_each_entry(trig, &trigger_list, next_trig) {
+ if (!led_trig_check_rgb(trig, led_cdev))
+ continue;
Omit RGB triggers when listing the available triggers for a non-RGB LED via sysfs.
if (led_cdev->trigger && !strcmp(led_cdev->trigger->name,
trig->name))
len += sprintf(buf+len, "[%s] ", trig->name);
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 58e22e6..07eb074 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -248,6 +248,9 @@ enum led_brightness led_hsv_to_rgb(enum led_brightness hsv);
struct led_trigger {
/* Trigger Properties */
const char *name;
+ u8 flags;
+#define LED_TRIG_CAP_RGB BIT(0)
+
void (*activate)(struct led_classdev *led_cdev);
void (*deactivate)(struct led_classdev *led_cdev);
--
Best regards,
Jacek Anaszewski