Re: [PATCH 1/3] leds: triggers: add support for RGB triggers

[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.

> > >    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.

> > >            }
> > >        }
> > >        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