* [RFC PATCH 0/1] leds: backlight: Register with class backlight
@ 2019-11-25 14:47 Guido Günther
2019-11-25 14:47 ` [RFC PATCH 1/1] leds: backlight: register with class backlight too Guido Günther
2019-11-25 18:19 ` [RFC PATCH 0/1] leds: backlight: Register with class backlight Jacek Anaszewski
0 siblings, 2 replies; 3+ messages in thread
From: Guido Günther @ 2019-11-25 14:47 UTC (permalink / raw)
To: Jacek Anaszewski, Pavel Machek, Dan Murphy, Kate Stewart,
Thomas Gleixner, Enrico Weigelt, Allison Randal, linux-leds,
linux-kernel
When using current LCD drivers as ledtrig backlight they're
not registered with the backlight device class. This has
two problems: they're usually not found by userspace since
these tools usually look in /sys/class/backlight and they
can't be used as backlight phandles in device tree for
e.g. LCD panels.
This is an RFC if this is worthwhile at all? A current problem
is that changing the LED brightness does currently not notify
the class backlight so they can get out of sync but i could
look into that if the approach makes sense.
Guido Günther (1):
leds: backlight: register with class backlight too
drivers/leds/trigger/ledtrig-backlight.c | 54 ++++++++++++++++++++++++
1 file changed, 54 insertions(+)
--
2.23.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* [RFC PATCH 1/1] leds: backlight: register with class backlight too
2019-11-25 14:47 [RFC PATCH 0/1] leds: backlight: Register with class backlight Guido Günther
@ 2019-11-25 14:47 ` Guido Günther
2019-11-25 18:19 ` [RFC PATCH 0/1] leds: backlight: Register with class backlight Jacek Anaszewski
1 sibling, 0 replies; 3+ messages in thread
From: Guido Günther @ 2019-11-25 14:47 UTC (permalink / raw)
To: Jacek Anaszewski, Pavel Machek, Dan Murphy, Kate Stewart,
Thomas Gleixner, Enrico Weigelt, Allison Randal, linux-leds,
linux-kernel
This allows it to be used as backlight device in device tree (e.g. to
link it to a LCD panel) and helps userspace since it shows up in
/sys/class/backlight then.
Signed-off-by: Guido Günther <agx@sigxcpu.org>
---
drivers/leds/trigger/ledtrig-backlight.c | 54 ++++++++++++++++++++++++
1 file changed, 54 insertions(+)
diff --git a/drivers/leds/trigger/ledtrig-backlight.c b/drivers/leds/trigger/ledtrig-backlight.c
index 487577d22cfc..3967f7014b9a 100644
--- a/drivers/leds/trigger/ledtrig-backlight.c
+++ b/drivers/leds/trigger/ledtrig-backlight.c
@@ -22,6 +22,9 @@ struct bl_trig_notifier {
int brightness;
int old_status;
struct notifier_block notifier;
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+ struct backlight_device *backlight_device;
+#endif
unsigned invert;
};
@@ -98,11 +101,40 @@ static struct attribute *bl_trig_attrs[] = {
};
ATTRIBUTE_GROUPS(bl_trig);
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+static int bl_get_brightness(struct backlight_device *b)
+{
+ struct led_classdev *led = bl_get_data(b);
+
+ return led_get_brightness(led);
+}
+
+static int bl_update_status(struct backlight_device *b)
+{
+ struct led_classdev *led = bl_get_data(b);
+
+ if (b->props.state & (BL_CORE_SUSPENDED | BL_CORE_FBBLANK))
+ led_set_brightness_nosleep(led, 0);
+ else
+ led_set_brightness_nosleep(led, b->props.brightness);
+
+ return 0;
+}
+
+static const struct backlight_ops backlight_ops = {
+ .get_brightness = bl_get_brightness,
+ .update_status = bl_update_status,
+};
+#endif
+
static int bl_trig_activate(struct led_classdev *led)
{
int ret;
struct bl_trig_notifier *n;
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+ struct backlight_properties props;
+#endif
n = kzalloc(sizeof(struct bl_trig_notifier), GFP_KERNEL);
if (!n)
@@ -118,13 +150,35 @@ static int bl_trig_activate(struct led_classdev *led)
if (ret)
dev_err(led->dev, "unable to register backlight trigger\n");
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+ memset(&props, 0, sizeof(struct backlight_properties));
+ props.type = BACKLIGHT_PLATFORM;
+ props.max_brightness = LED_FULL;
+ props.brightness = led->brightness;
+ n->backlight_device = backlight_device_register(led->name,
+ led->dev,
+ led,
+ &backlight_ops,
+ &props);
+ if (IS_ERR(n->backlight_device)) {
+ ret = IS_ERR(n->backlight_device);
+ goto out;
+ }
+#endif
+
return 0;
+out:
+ fb_unregister_client(&n->notifier);
+ return ret;
}
static void bl_trig_deactivate(struct led_classdev *led)
{
struct bl_trig_notifier *n = led_get_trigger_data(led);
+#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
+ backlight_device_unregister(n->backlight_device);
+#endif
fb_unregister_client(&n->notifier);
kfree(n);
}
--
2.23.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [RFC PATCH 0/1] leds: backlight: Register with class backlight
2019-11-25 14:47 [RFC PATCH 0/1] leds: backlight: Register with class backlight Guido Günther
2019-11-25 14:47 ` [RFC PATCH 1/1] leds: backlight: register with class backlight too Guido Günther
@ 2019-11-25 18:19 ` Jacek Anaszewski
1 sibling, 0 replies; 3+ messages in thread
From: Jacek Anaszewski @ 2019-11-25 18:19 UTC (permalink / raw)
To: Guido Günther, Pavel Machek, Dan Murphy, Kate Stewart,
Thomas Gleixner, Enrico Weigelt, Allison Randal, linux-leds,
linux-kernel
Hi Guido,
You might want to check the pending patch set [0].
On 11/25/19 3:47 PM, Guido Günther wrote:
> When using current LCD drivers as ledtrig backlight they're
> not registered with the backlight device class. This has
> two problems: they're usually not found by userspace since
> these tools usually look in /sys/class/backlight and they
> can't be used as backlight phandles in device tree for
> e.g. LCD panels.
>
> This is an RFC if this is worthwhile at all? A current problem
> is that changing the LED brightness does currently not notify
> the class backlight so they can get out of sync but i could
> look into that if the approach makes sense.
>
>
> Guido Günther (1):
> leds: backlight: register with class backlight too
>
> drivers/leds/trigger/ledtrig-backlight.c | 54 ++++++++++++++++++++++++
> 1 file changed, 54 insertions(+)
>
[0]
https://lore.kernel.org/linux-leds/20191007124437.20367-1-jjhiblot@ti.com/
--
Best regards,
Jacek Anaszewski
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-11-25 14:47 [RFC PATCH 0/1] leds: backlight: Register with class backlight Guido Günther
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