[PATCH v3 0/4] Add a generic driver for LED-based backlight

[PATCH v3 0/4] Add a generic driver for LED-based backlight

[Jean-Jacques Hiblot]

This series aims to add a led-backlight driver, similar to pwm-backlight,
but using a LED class device underneath.

A few years ago (2015), Tomi Valkeinen posted a series implementing a
backlight driver on top of a LED device:
https://patchwork.kernel.org/patch/7293991/
https://patchwork.kernel.org/patch/7294001/
https://patchwork.kernel.org/patch/7293981/

The discussion stopped because Tomi lacked the time to work on it.

changes in v3:
- dt binding: don't limit the brightness range to 0-255. Use the range of
  the underlying LEDs. as a side-effect, all LEDs must now have the same
  range
- driver: Adapt to dt binding update.
- driver: rework probe() for clarity and remove the remaining goto.

changes in v2:
- handle more than one LED.
- don't make the backlight device a child of the LED controller.
- make brightness-levels and default-brightness-level optionnal
- removed the option to use a GPIO enable.
- removed the option to use a regulator. It should be handled by the LED core
- don't make any change to the LED core (not needed anymore)

Jean-Jacques Hiblot (2):
  leds: Add managed API to get a LED from a device driver
  dt-bindings: backlight: Add led-backlight binding

Tomi Valkeinen (2):
  leds: Add of_led_get() and led_put()
  backlight: add led-backlight driver

 .../bindings/leds/backlight/led-backlight.txt |  28 ++
 drivers/leds/led-class.c                      |  92 ++++++
 drivers/video/backlight/Kconfig               |   7 +
 drivers/video/backlight/Makefile              |   1 +
 drivers/video/backlight/led_bl.c              | 268 ++++++++++++++++++
 include/linux/leds.h                          |   6 +
 6 files changed, 402 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
 create mode 100644 drivers/video/backlight/led_bl.c

-- 
2.17.1

[PATCH v3 0/4] Add a generic driver for LED-based backlight

[Jean-Jacques Hiblot]

This series aims to add a led-backlight driver, similar to pwm-backlight,
but using a LED class device underneath.

A few years ago (2015), Tomi Valkeinen posted a series implementing a
backlight driver on top of a LED device:
https://patchwork.kernel.org/patch/7293991/
https://patchwork.kernel.org/patch/7294001/
https://patchwork.kernel.org/patch/7293981/

The discussion stopped because Tomi lacked the time to work on it.

changes in v3:
- dt binding: don't limit the brightness range to 0-255. Use the range of
  the underlying LEDs. as a side-effect, all LEDs must now have the same
  range
- driver: Adapt to dt binding update.
- driver: rework probe() for clarity and remove the remaining goto.

changes in v2:
- handle more than one LED.
- don't make the backlight device a child of the LED controller.
- make brightness-levels and default-brightness-level optionnal
- removed the option to use a GPIO enable.
- removed the option to use a regulator. It should be handled by the LED core
- don't make any change to the LED core (not needed anymore)

Jean-Jacques Hiblot (2):
  leds: Add managed API to get a LED from a device driver
  dt-bindings: backlight: Add led-backlight binding

Tomi Valkeinen (2):
  leds: Add of_led_get() and led_put()
  backlight: add led-backlight driver

 .../bindings/leds/backlight/led-backlight.txt |  28 ++
 drivers/leds/led-class.c                      |  92 ++++++
 drivers/video/backlight/Kconfig               |   7 +
 drivers/video/backlight/Makefile              |   1 +
 drivers/video/backlight/led_bl.c              | 268 ++++++++++++++++++
 include/linux/leds.h                          |   6 +
 6 files changed, 402 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
 create mode 100644 drivers/video/backlight/led_bl.c

-- 
2.17.1

[PATCH v3 1/4] leds: Add of_led_get() and led_put()

[Jean-Jacques Hiblot]

From: Tomi Valkeinen <tomi.valkeinen@ti.com>

This patch adds basic support for a kernel driver to get a LED device.
This will be used by the led-backlight driver.

Only OF version is implemented for now, and the behavior is similar to
PWM's of_pwm_get() and pwm_put().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 drivers/leds/led-class.c | 50 ++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h     |  4 ++++
 2 files changed, 54 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index e01b2d982564..0f67b13b0f1f 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -19,6 +19,7 @@
 #include <linux/timer.h>
 #include <linux/regulator/consumer.h>
 #include <uapi/linux/uleds.h>
+#include <linux/of.h>
 #include "leds.h"
 
 static struct class *leds_class;
@@ -214,6 +215,55 @@ static int led_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
 
+static int led_match_led_node(struct device *led_dev, const void *data)
+{
+	return led_dev->of_node == data ? 1 : 0;
+}
+
+/**
+ * of_led_get() - request a LED device via the LED framework
+ * @np: device node to get the LED device from
+ * @index: the index of the LED
+ *
+ * Returns the LED device parsed from the phandle specified in the "leds"
+ * property of a device tree node or a negative error-code on failure.
+ */
+struct led_classdev *of_led_get(struct device_node *np, int index)
+{
+	struct device *led_dev;
+	struct led_classdev *led_cdev;
+	struct device_node *led_node;
+
+	led_node = of_parse_phandle(np, "leds", index);
+	if (!led_node)
+		return ERR_PTR(-ENOENT);
+
+	led_dev = class_find_device(leds_class, NULL, led_node,
+		led_match_led_node);
+	of_node_put(led_node);
+
+	if (!led_dev)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	led_cdev = dev_get_drvdata(led_dev);
+
+	if (!try_module_get(led_cdev->dev->parent->driver->owner))
+		return ERR_PTR(-ENODEV);
+
+	return led_cdev;
+}
+EXPORT_SYMBOL_GPL(of_led_get);
+
+/**
+ * led_put() - release a LED device
+ * @led_cdev: LED device
+ */
+void led_put(struct led_classdev *led_cdev)
+{
+	module_put(led_cdev->dev->parent->driver->owner);
+}
+EXPORT_SYMBOL_GPL(led_put);
+
 static int match_name(struct device *dev, const void *data)
 {
 	if (!dev_name(dev))
diff --git a/include/linux/leds.h b/include/linux/leds.h
index bee8e3f8dddd..0a71c7cdd191 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -19,6 +19,7 @@
 
 struct device;
 struct led_pattern;
+struct device_node;
 /*
  * LED Core
  */
@@ -145,6 +146,9 @@ extern void devm_led_classdev_unregister(struct device *parent,
 extern void led_classdev_suspend(struct led_classdev *led_cdev);
 extern void led_classdev_resume(struct led_classdev *led_cdev);
 
+extern struct led_classdev *of_led_get(struct device_node *np, int index);
+extern void led_put(struct led_classdev *led_cdev);
+
 /**
  * led_blink_set - set blinking with software fallback
  * @led_cdev: the LED to start blinking
-- 
2.17.1

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[PATCH v3 1/4] leds: Add of_led_get() and led_put()

[Jean-Jacques Hiblot]

From: Tomi Valkeinen <tomi.valkeinen@ti.com>

This patch adds basic support for a kernel driver to get a LED device.
This will be used by the led-backlight driver.

Only OF version is implemented for now, and the behavior is similar to
PWM's of_pwm_get() and pwm_put().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 drivers/leds/led-class.c | 50 ++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h     |  4 ++++
 2 files changed, 54 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index e01b2d982564..0f67b13b0f1f 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -19,6 +19,7 @@
 #include <linux/timer.h>
 #include <linux/regulator/consumer.h>
 #include <uapi/linux/uleds.h>
+#include <linux/of.h>
 #include "leds.h"
 
 static struct class *leds_class;
@@ -214,6 +215,55 @@ static int led_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
 
+static int led_match_led_node(struct device *led_dev, const void *data)
+{
+	return led_dev->of_node == data ? 1 : 0;
+}
+
+/**
+ * of_led_get() - request a LED device via the LED framework
+ * @np: device node to get the LED device from
+ * @index: the index of the LED
+ *
+ * Returns the LED device parsed from the phandle specified in the "leds"
+ * property of a device tree node or a negative error-code on failure.
+ */
+struct led_classdev *of_led_get(struct device_node *np, int index)
+{
+	struct device *led_dev;
+	struct led_classdev *led_cdev;
+	struct device_node *led_node;
+
+	led_node = of_parse_phandle(np, "leds", index);
+	if (!led_node)
+		return ERR_PTR(-ENOENT);
+
+	led_dev = class_find_device(leds_class, NULL, led_node,
+		led_match_led_node);
+	of_node_put(led_node);
+
+	if (!led_dev)
+		return ERR_PTR(-EPROBE_DEFER);
+
+	led_cdev = dev_get_drvdata(led_dev);
+
+	if (!try_module_get(led_cdev->dev->parent->driver->owner))
+		return ERR_PTR(-ENODEV);
+
+	return led_cdev;
+}
+EXPORT_SYMBOL_GPL(of_led_get);
+
+/**
+ * led_put() - release a LED device
+ * @led_cdev: LED device
+ */
+void led_put(struct led_classdev *led_cdev)
+{
+	module_put(led_cdev->dev->parent->driver->owner);
+}
+EXPORT_SYMBOL_GPL(led_put);
+
 static int match_name(struct device *dev, const void *data)
 {
 	if (!dev_name(dev))
diff --git a/include/linux/leds.h b/include/linux/leds.h
index bee8e3f8dddd..0a71c7cdd191 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -19,6 +19,7 @@
 
 struct device;
 struct led_pattern;
+struct device_node;
 /*
  * LED Core
  */
@@ -145,6 +146,9 @@ extern void devm_led_classdev_unregister(struct device *parent,
 extern void led_classdev_suspend(struct led_classdev *led_cdev);
 extern void led_classdev_resume(struct led_classdev *led_cdev);
 
+extern struct led_classdev *of_led_get(struct device_node *np, int index);
+extern void led_put(struct led_classdev *led_cdev);
+
 /**
  * led_blink_set - set blinking with software fallback
  * @led_cdev: the LED to start blinking
-- 
2.17.1

[PATCH v3 2/4] leds: Add managed API to get a LED from a device driver

[Jean-Jacques Hiblot]

If the LED is acquired by a consumer device with devm_led_get(), it is
automatically release when the device is detach.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 drivers/leds/led-class.c | 42 ++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h     |  2 ++
 2 files changed, 44 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 0f67b13b0f1f..521cb76fbaf7 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -264,6 +264,48 @@ void led_put(struct led_classdev *led_cdev)
 }
 EXPORT_SYMBOL_GPL(led_put);
 
+static void devm_led_release(struct device *dev, void *res)
+{
+	struct led_classdev **p = res;
+
+	led_put(*p);
+}
+
+/**
+ * devm_led_get - Resource-managed request of a LED device
+ * @dev:	LED consumer
+ * @idx:	index of the LED to obtain in the consumer
+ *
+ * The device node of the device is parse to find the request LED device.
+ * The LED device returned from this function is automatically released
+ * on driver detach.
+ *
+ * @return a pointer to a LED device or ERR_PTR(errno) on failure.
+ */
+struct led_classdev *__must_check devm_led_get(struct device *dev,
+					       int index)
+{
+	struct led_classdev *led;
+	struct led_classdev **dr;
+
+	led = of_led_get(dev->of_node, index);
+	if (IS_ERR(led))
+		return led;
+
+	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
+			  GFP_KERNEL);
+	if (!dr) {
+		led_put(led);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	*dr = led;
+	devres_add(dev, dr);
+
+	return led;
+}
+EXPORT_SYMBOL_GPL(devm_led_get);
+
 static int match_name(struct device *dev, const void *data)
 {
 	if (!dev_name(dev))
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 0a71c7cdd191..7fcec566d774 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -148,6 +148,8 @@ extern void led_classdev_resume(struct led_classdev *led_cdev);
 
 extern struct led_classdev *of_led_get(struct device_node *np, int index);
 extern void led_put(struct led_classdev *led_cdev);
+struct led_classdev *__must_check devm_led_get(struct device *dev,
+					       int index);
 
 /**
  * led_blink_set - set blinking with software fallback
-- 
2.17.1

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[PATCH v3 2/4] leds: Add managed API to get a LED from a device driver

[Jean-Jacques Hiblot]

If the LED is acquired by a consumer device with devm_led_get(), it is
automatically release when the device is detach.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 drivers/leds/led-class.c | 42 ++++++++++++++++++++++++++++++++++++++++
 include/linux/leds.h     |  2 ++
 2 files changed, 44 insertions(+)

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 0f67b13b0f1f..521cb76fbaf7 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -264,6 +264,48 @@ void led_put(struct led_classdev *led_cdev)
 }
 EXPORT_SYMBOL_GPL(led_put);
 
+static void devm_led_release(struct device *dev, void *res)
+{
+	struct led_classdev **p = res;
+
+	led_put(*p);
+}
+
+/**
+ * devm_led_get - Resource-managed request of a LED device
+ * @dev:	LED consumer
+ * @idx:	index of the LED to obtain in the consumer
+ *
+ * The device node of the device is parse to find the request LED device.
+ * The LED device returned from this function is automatically released
+ * on driver detach.
+ *
+ * @return a pointer to a LED device or ERR_PTR(errno) on failure.
+ */
+struct led_classdev *__must_check devm_led_get(struct device *dev,
+					       int index)
+{
+	struct led_classdev *led;
+	struct led_classdev **dr;
+
+	led = of_led_get(dev->of_node, index);
+	if (IS_ERR(led))
+		return led;
+
+	dr = devres_alloc(devm_led_release, sizeof(struct led_classdev *),
+			  GFP_KERNEL);
+	if (!dr) {
+		led_put(led);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	*dr = led;
+	devres_add(dev, dr);
+
+	return led;
+}
+EXPORT_SYMBOL_GPL(devm_led_get);
+
 static int match_name(struct device *dev, const void *data)
 {
 	if (!dev_name(dev))
diff --git a/include/linux/leds.h b/include/linux/leds.h
index 0a71c7cdd191..7fcec566d774 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -148,6 +148,8 @@ extern void led_classdev_resume(struct led_classdev *led_cdev);
 
 extern struct led_classdev *of_led_get(struct device_node *np, int index);
 extern void led_put(struct led_classdev *led_cdev);
+struct led_classdev *__must_check devm_led_get(struct device *dev,
+					       int index);
 
 /**
  * led_blink_set - set blinking with software fallback
-- 
2.17.1

[PATCH v3 3/4] dt-bindings: backlight: Add led-backlight binding

[Jean-Jacques Hiblot]

Add DT binding for led-backlight.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt

diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
new file mode 100644
index 000000000000..0444eec8efe1
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
@@ -0,0 +1,28 @@
+led-backlight bindings
+
+This binding is used to describe a basic backlight device made of LEDs.
+It can also be used to describe a backlight device controlled by the output of
+a LED driver.
+
+Required properties:
+  - compatible: "led-backlight"
+  - leds: a list of LEDs
+
+Optional properties:
+  - brightness-levels: Array of distinct brightness levels. The levels must be
+                       in the range accepted by the underlying LED devices.
+                       This is used to translate a backlight brightness level
+                       into a LED brightness level. if not provided, the
+                       identity mapping is used.
+
+  - default-brightness-level: The default brightness level.
+
+Example:
+
+	backlight {
+		compatible = "led-backlight";
+
+		leds = <&led1>, <&led2>;
+		brightness-levels = <0 4 8 16 32 64 128 255>;
+		default-brightness-level = <6>;
+	};
-- 
2.17.1

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[PATCH v3 3/4] dt-bindings: backlight: Add led-backlight binding

[Jean-Jacques Hiblot]

Add DT binding for led-backlight.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt

diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
new file mode 100644
index 000000000000..0444eec8efe1
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
@@ -0,0 +1,28 @@
+led-backlight bindings
+
+This binding is used to describe a basic backlight device made of LEDs.
+It can also be used to describe a backlight device controlled by the output of
+a LED driver.
+
+Required properties:
+  - compatible: "led-backlight"
+  - leds: a list of LEDs
+
+Optional properties:
+  - brightness-levels: Array of distinct brightness levels. The levels must be
+                       in the range accepted by the underlying LED devices.
+                       This is used to translate a backlight brightness level
+                       into a LED brightness level. if not provided, the
+                       identity mapping is used.
+
+  - default-brightness-level: The default brightness level.
+
+Example:
+
+	backlight {
+		compatible = "led-backlight";
+
+		leds = <&led1>, <&led2>;
+		brightness-levels = <0 4 8 16 32 64 128 255>;
+		default-brightness-level = <6>;
+	};
-- 
2.17.1

[PATCH v3 4/4] backlight: add led-backlight driver

[Jean-Jacques Hiblot]

From: Tomi Valkeinen <tomi.valkeinen@ti.com>

This patch adds a led-backlight driver (led_bl), which is similar to
pwm_bl except the driver uses a LED class driver to adjust the
brightness in the HW. Multiple LEDs can be used for a single backlight.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 drivers/video/backlight/Kconfig  |   7 +
 drivers/video/backlight/Makefile |   1 +
 drivers/video/backlight/led_bl.c | 268 +++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/video/backlight/led_bl.c

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 8b081d61773e..585a1787618c 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -458,6 +458,13 @@ config BACKLIGHT_RAVE_SP
 	help
 	  Support for backlight control on RAVE SP device.
 
+config BACKLIGHT_LED
+	tristate "Generic LED based Backlight Driver"
+	depends on LEDS_CLASS && OF
+	help
+	  If you have a LCD backlight adjustable by LED class driver, say Y
+	  to enable this driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endmenu
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 63c507c07437..2a67642966a5 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -57,3 +57,4 @@ obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
 obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
 obj-$(CONFIG_BACKLIGHT_RAVE_SP)		+= rave-sp-backlight.o
+obj-$(CONFIG_BACKLIGHT_LED)		+= led_bl.o
diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c
new file mode 100644
index 000000000000..58153150a618
--- /dev/null
+++ b/drivers/video/backlight/led_bl.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Texas Instruments Incorporated -  http://www.ti.com/
+ * Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
+ *
+ * Based on pwm_bl.c
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define BKL_FULL_BRIGHTNESS 255
+
+struct led_bl_data {
+	struct device		*dev;
+	struct backlight_device	*bl_dev;
+	struct led_classdev	**leds;
+	bool			enabled;
+	int			nb_leds;
+	unsigned int		*levels;
+	unsigned int		default_brightness;
+	unsigned int		max_brightness;
+};
+
+static int to_led_brightness(struct led_classdev *led, int value)
+{
+	return (value * led->max_brightness) / BKL_FULL_BRIGHTNESS;
+}
+
+static void led_bl_set_brightness(struct led_bl_data *priv, int level)
+{
+	int i;
+	int bkl_brightness;
+
+	if (priv->levels)
+		bkl_brightness = priv->levels[level];
+	else
+		bkl_brightness = level;
+
+	for (i = 0; i < priv->nb_leds; i++) {
+		int led_brightness;
+		struct led_classdev *led = priv->leds[i];
+
+		led_brightness = to_led_brightness(led, bkl_brightness);
+		led_set_brightness(led, led_brightness);
+	}
+
+	priv->enabled = true;
+}
+
+static void led_bl_power_off(struct led_bl_data *priv)
+{
+	int i;
+
+	if (!priv->enabled)
+		return;
+
+	for (i = 0; i < priv->nb_leds; i++)
+		led_set_brightness(priv->leds[i], LED_OFF);
+
+	priv->enabled = false;
+}
+
+static int led_bl_update_status(struct backlight_device *bl)
+{
+	struct led_bl_data *priv = bl_get_data(bl);
+	int brightness = bl->props.brightness;
+
+	if (bl->props.power != FB_BLANK_UNBLANK ||
+	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
+	    bl->props.state & BL_CORE_FBBLANK)
+		brightness = 0;
+
+	if (brightness > 0)
+		led_bl_set_brightness(priv, brightness);
+	else
+		led_bl_power_off(priv);
+
+	return 0;
+}
+
+static const struct backlight_ops led_bl_ops = {
+	.update_status	= led_bl_update_status,
+};
+
+static int led_bl_get_leds(struct device *dev,
+			   struct led_bl_data *priv)
+{
+	int i, nb_leds, ret;
+	struct device_node *node = dev->of_node;
+	struct led_classdev **leds;
+	unsigned int max_brightness;
+	unsigned int default_brightness;
+
+	ret = of_count_phandle_with_args(node, "leds", NULL);
+	if (ret < 0) {
+		dev_err(dev, "unable to get led count\n");
+		return -EINVAL;
+	}
+
+	nb_leds = ret;
+	if (nb_leds < 1) {
+		dev_err(dev, "At least one LED must be specified!\n");
+		return -EINVAL;
+	}
+
+	leds = devm_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,
+			    GFP_KERNEL);
+	if (!leds)
+		return -ENOMEM;
+
+	for (i = 0; i < nb_leds; i++) {
+		leds[i] = devm_led_get(dev, i);
+		if (IS_ERR(leds[i]))
+			return PTR_ERR(leds[i]);
+	}
+
+	/* check that the LEDs all have the same brightness range */
+	max_brightness = leds[0]->max_brightness;
+	for (i = 1; i < nb_leds; i++) {
+		if (max_brightness != leds[i]->max_brightness) {
+			dev_err(dev, "LEDs must have identical ranges\n");
+			return -EINVAL;
+		}
+	}
+
+	/* get the default brightness from the first LED from the list */
+	default_brightness = leds[0]->brightness;
+
+	priv->nb_leds = nb_leds;
+	priv->leds = leds;
+	priv->max_brightness = max_brightness;
+	priv->default_brightness = default_brightness;
+
+	return 0;
+}
+
+static int led_bl_parse_levels(struct device *dev,
+			   struct led_bl_data *priv)
+{
+	struct device_node *node = dev->of_node;
+	int num_levels;
+	u32 value;
+	int ret;
+
+	if (!node)
+		return -ENODEV;
+
+	num_levels = of_property_count_u32_elems(node, "brightness-levels");
+	if (num_levels > 1) {
+		int i;
+		unsigned int db;
+		u32 *levels = NULL;
+
+		levels = devm_kzalloc(dev, sizeof(u32) * num_levels,
+				      GFP_KERNEL);
+		if (!levels)
+			return -ENOMEM;
+
+		ret = of_property_read_u32_array(node, "brightness-levels",
+						levels,
+						num_levels);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 *try to map actual LED brightness to backlight brightness
+		 * level
+		 */
+		db = priv->default_brightness;
+		for (i = 0 ; i < num_levels; i++) {
+			if ((i && db > levels[i-1]) && db <= levels[i])
+				break;
+		}
+		priv->default_brightness = i;
+		priv->max_brightness = num_levels - 1;
+		priv->levels = levels;
+	} else if (num_levels >= 0)
+		dev_warn(dev, "not enought levels defined\n");
+
+	ret = of_property_read_u32(node, "default-brightness-level", &value);
+	if (!ret && value <= priv->max_brightness)
+		priv->default_brightness = value;
+	else if (!ret  && value > priv->max_brightness)
+		dev_warn(dev, "invalid default brightness. ignoring it\n");
+
+	return 0;
+}
+
+static int led_bl_probe(struct platform_device *pdev)
+{
+	struct backlight_properties props;
+	struct led_bl_data *priv;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->dev = &pdev->dev;
+
+	ret = led_bl_get_leds(&pdev->dev, priv);
+	if (ret)
+		return ret;
+
+	ret = led_bl_parse_levels(&pdev->dev, priv);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to parse DT data\n");
+		return ret;
+	}
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = priv->max_brightness;
+	props.brightness = priv->default_brightness;
+	props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN :
+		      FB_BLANK_UNBLANK;
+	priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
+			&pdev->dev, priv, &led_bl_ops, &props);
+	if (IS_ERR(priv->bl_dev)) {
+		dev_err(&pdev->dev, "failed to register backlight\n");
+		return PTR_ERR(priv->bl_dev);
+	}
+
+	backlight_update_status(priv->bl_dev);
+
+	return 0;
+}
+
+static int led_bl_remove(struct platform_device *pdev)
+{
+	struct led_bl_data *priv = platform_get_drvdata(pdev);
+	struct backlight_device *bl = priv->bl_dev;
+
+	backlight_device_unregister(bl);
+
+	led_bl_power_off(priv);
+
+	return 0;
+}
+
+static const struct of_device_id led_bl_of_match[] = {
+	{ .compatible = "led-backlight" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, led_bl_of_match);
+
+static struct platform_driver led_bl_driver = {
+	.driver		= {
+		.name		= "led-backlight",
+		.of_match_table	= of_match_ptr(led_bl_of_match),
+	},
+	.probe		= led_bl_probe,
+	.remove		= led_bl_remove,
+};
+
+module_platform_driver(led_bl_driver);
+
+MODULE_DESCRIPTION("LED based Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:led-backlight");
-- 
2.17.1

[PATCH v3 4/4] backlight: add led-backlight driver

[Jean-Jacques Hiblot]

From: Tomi Valkeinen <tomi.valkeinen@ti.com>

This patch adds a led-backlight driver (led_bl), which is similar to
pwm_bl except the driver uses a LED class driver to adjust the
brightness in the HW. Multiple LEDs can be used for a single backlight.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
---
 drivers/video/backlight/Kconfig  |   7 +
 drivers/video/backlight/Makefile |   1 +
 drivers/video/backlight/led_bl.c | 268 +++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/video/backlight/led_bl.c

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 8b081d61773e..585a1787618c 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -458,6 +458,13 @@ config BACKLIGHT_RAVE_SP
 	help
 	  Support for backlight control on RAVE SP device.
 
+config BACKLIGHT_LED
+	tristate "Generic LED based Backlight Driver"
+	depends on LEDS_CLASS && OF
+	help
+	  If you have a LCD backlight adjustable by LED class driver, say Y
+	  to enable this driver.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endmenu
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index 63c507c07437..2a67642966a5 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -57,3 +57,4 @@ obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
 obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
 obj-$(CONFIG_BACKLIGHT_RAVE_SP)		+= rave-sp-backlight.o
+obj-$(CONFIG_BACKLIGHT_LED)		+= led_bl.o
diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c
new file mode 100644
index 000000000000..58153150a618
--- /dev/null
+++ b/drivers/video/backlight/led_bl.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2015-2019 Texas Instruments Incorporated -  http://www.ti.com/
+ * Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
+ *
+ * Based on pwm_bl.c
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define BKL_FULL_BRIGHTNESS 255
+
+struct led_bl_data {
+	struct device		*dev;
+	struct backlight_device	*bl_dev;
+	struct led_classdev	**leds;
+	bool			enabled;
+	int			nb_leds;
+	unsigned int		*levels;
+	unsigned int		default_brightness;
+	unsigned int		max_brightness;
+};
+
+static int to_led_brightness(struct led_classdev *led, int value)
+{
+	return (value * led->max_brightness) / BKL_FULL_BRIGHTNESS;
+}
+
+static void led_bl_set_brightness(struct led_bl_data *priv, int level)
+{
+	int i;
+	int bkl_brightness;
+
+	if (priv->levels)
+		bkl_brightness = priv->levels[level];
+	else
+		bkl_brightness = level;
+
+	for (i = 0; i < priv->nb_leds; i++) {
+		int led_brightness;
+		struct led_classdev *led = priv->leds[i];
+
+		led_brightness = to_led_brightness(led, bkl_brightness);
+		led_set_brightness(led, led_brightness);
+	}
+
+	priv->enabled = true;
+}
+
+static void led_bl_power_off(struct led_bl_data *priv)
+{
+	int i;
+
+	if (!priv->enabled)
+		return;
+
+	for (i = 0; i < priv->nb_leds; i++)
+		led_set_brightness(priv->leds[i], LED_OFF);
+
+	priv->enabled = false;
+}
+
+static int led_bl_update_status(struct backlight_device *bl)
+{
+	struct led_bl_data *priv = bl_get_data(bl);
+	int brightness = bl->props.brightness;
+
+	if (bl->props.power != FB_BLANK_UNBLANK ||
+	    bl->props.fb_blank != FB_BLANK_UNBLANK ||
+	    bl->props.state & BL_CORE_FBBLANK)
+		brightness = 0;
+
+	if (brightness > 0)
+		led_bl_set_brightness(priv, brightness);
+	else
+		led_bl_power_off(priv);
+
+	return 0;
+}
+
+static const struct backlight_ops led_bl_ops = {
+	.update_status	= led_bl_update_status,
+};
+
+static int led_bl_get_leds(struct device *dev,
+			   struct led_bl_data *priv)
+{
+	int i, nb_leds, ret;
+	struct device_node *node = dev->of_node;
+	struct led_classdev **leds;
+	unsigned int max_brightness;
+	unsigned int default_brightness;
+
+	ret = of_count_phandle_with_args(node, "leds", NULL);
+	if (ret < 0) {
+		dev_err(dev, "unable to get led count\n");
+		return -EINVAL;
+	}
+
+	nb_leds = ret;
+	if (nb_leds < 1) {
+		dev_err(dev, "At least one LED must be specified!\n");
+		return -EINVAL;
+	}
+
+	leds = devm_kzalloc(dev, sizeof(struct led_classdev *) * nb_leds,
+			    GFP_KERNEL);
+	if (!leds)
+		return -ENOMEM;
+
+	for (i = 0; i < nb_leds; i++) {
+		leds[i] = devm_led_get(dev, i);
+		if (IS_ERR(leds[i]))
+			return PTR_ERR(leds[i]);
+	}
+
+	/* check that the LEDs all have the same brightness range */
+	max_brightness = leds[0]->max_brightness;
+	for (i = 1; i < nb_leds; i++) {
+		if (max_brightness != leds[i]->max_brightness) {
+			dev_err(dev, "LEDs must have identical ranges\n");
+			return -EINVAL;
+		}
+	}
+
+	/* get the default brightness from the first LED from the list */
+	default_brightness = leds[0]->brightness;
+
+	priv->nb_leds = nb_leds;
+	priv->leds = leds;
+	priv->max_brightness = max_brightness;
+	priv->default_brightness = default_brightness;
+
+	return 0;
+}
+
+static int led_bl_parse_levels(struct device *dev,
+			   struct led_bl_data *priv)
+{
+	struct device_node *node = dev->of_node;
+	int num_levels;
+	u32 value;
+	int ret;
+
+	if (!node)
+		return -ENODEV;
+
+	num_levels = of_property_count_u32_elems(node, "brightness-levels");
+	if (num_levels > 1) {
+		int i;
+		unsigned int db;
+		u32 *levels = NULL;
+
+		levels = devm_kzalloc(dev, sizeof(u32) * num_levels,
+				      GFP_KERNEL);
+		if (!levels)
+			return -ENOMEM;
+
+		ret = of_property_read_u32_array(node, "brightness-levels",
+						levels,
+						num_levels);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 *try to map actual LED brightness to backlight brightness
+		 * level
+		 */
+		db = priv->default_brightness;
+		for (i = 0 ; i < num_levels; i++) {
+			if ((i && db > levels[i-1]) && db <= levels[i])
+				break;
+		}
+		priv->default_brightness = i;
+		priv->max_brightness = num_levels - 1;
+		priv->levels = levels;
+	} else if (num_levels >= 0)
+		dev_warn(dev, "not enought levels defined\n");
+
+	ret = of_property_read_u32(node, "default-brightness-level", &value);
+	if (!ret && value <= priv->max_brightness)
+		priv->default_brightness = value;
+	else if (!ret  && value > priv->max_brightness)
+		dev_warn(dev, "invalid default brightness. ignoring it\n");
+
+	return 0;
+}
+
+static int led_bl_probe(struct platform_device *pdev)
+{
+	struct backlight_properties props;
+	struct led_bl_data *priv;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->dev = &pdev->dev;
+
+	ret = led_bl_get_leds(&pdev->dev, priv);
+	if (ret)
+		return ret;
+
+	ret = led_bl_parse_levels(&pdev->dev, priv);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to parse DT data\n");
+		return ret;
+	}
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
+	props.max_brightness = priv->max_brightness;
+	props.brightness = priv->default_brightness;
+	props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN :
+		      FB_BLANK_UNBLANK;
+	priv->bl_dev = backlight_device_register(dev_name(&pdev->dev),
+			&pdev->dev, priv, &led_bl_ops, &props);
+	if (IS_ERR(priv->bl_dev)) {
+		dev_err(&pdev->dev, "failed to register backlight\n");
+		return PTR_ERR(priv->bl_dev);
+	}
+
+	backlight_update_status(priv->bl_dev);
+
+	return 0;
+}
+
+static int led_bl_remove(struct platform_device *pdev)
+{
+	struct led_bl_data *priv = platform_get_drvdata(pdev);
+	struct backlight_device *bl = priv->bl_dev;
+
+	backlight_device_unregister(bl);
+
+	led_bl_power_off(priv);
+
+	return 0;
+}
+
+static const struct of_device_id led_bl_of_match[] = {
+	{ .compatible = "led-backlight" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, led_bl_of_match);
+
+static struct platform_driver led_bl_driver = {
+	.driver		= {
+		.name		= "led-backlight",
+		.of_match_table	= of_match_ptr(led_bl_of_match),
+	},
+	.probe		= led_bl_probe,
+	.remove		= led_bl_remove,
+};
+
+module_platform_driver(led_bl_driver);
+
+MODULE_DESCRIPTION("LED based Backlight Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:led-backlight");
-- 
2.17.1

Re: [PATCH v3 1/4] leds: Add of_led_get() and led_put()

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 1281 bytes --]

On Wed 2019-07-10 14:39:29, Jean-Jacques Hiblot wrote:
> From: Tomi Valkeinen <tomi.valkeinen@ti.com>
> 
> This patch adds basic support for a kernel driver to get a LED device.
> This will be used by the led-backlight driver.
> 
> Only OF version is implemented for now, and the behavior is similar to
> PWM's of_pwm_get() and pwm_put().
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>


> @@ -214,6 +215,55 @@ static int led_resume(struct device *dev)
>  
>  static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
>  
> +static int led_match_led_node(struct device *led_dev, const void *data)
> +{
> +	return led_dev->of_node == data ? 1 : 0;
> +}

Get rid of the "? 1 : 0"?


> +	led_node = of_parse_phandle(np, "leds", index);
> +	if (!led_node)
> +		return ERR_PTR(-ENOENT);
> +	led_dev = class_find_device(leds_class, NULL, led_node,
> +		led_match_led_node);
> +	of_node_put(led_node);
> +
> +	if (!led_dev)
> +		return ERR_PTR(-EPROBE_DEFER);

Won't this defer probe "forever" when the driver is not available?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 1/4] leds: Add of_led_get() and led_put()

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 1281 bytes --]

On Wed 2019-07-10 14:39:29, Jean-Jacques Hiblot wrote:
> From: Tomi Valkeinen <tomi.valkeinen@ti.com>
> 
> This patch adds basic support for a kernel driver to get a LED device.
> This will be used by the led-backlight driver.
> 
> Only OF version is implemented for now, and the behavior is similar to
> PWM's of_pwm_get() and pwm_put().
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>


> @@ -214,6 +215,55 @@ static int led_resume(struct device *dev)
>  
>  static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
>  
> +static int led_match_led_node(struct device *led_dev, const void *data)
> +{
> +	return led_dev->of_node == data ? 1 : 0;
> +}

Get rid of the "? 1 : 0"?


> +	led_node = of_parse_phandle(np, "leds", index);
> +	if (!led_node)
> +		return ERR_PTR(-ENOENT);
> +	led_dev = class_find_device(leds_class, NULL, led_node,
> +		led_match_led_node);
> +	of_node_put(led_node);
> +
> +	if (!led_dev)
> +		return ERR_PTR(-EPROBE_DEFER);

Won't this defer probe "forever" when the driver is not available?

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 2/4] leds: Add managed API to get a LED from a device driver

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 401 bytes --]

On Wed 2019-07-10 14:39:30, Jean-Jacques Hiblot wrote:
> If the LED is acquired by a consumer device with devm_led_get(), it is
> automatically release when the device is detach.

released, detached.

Acked-by: Pavel Machek <pavel@ucw.cz>
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 2/4] leds: Add managed API to get a LED from a device driver

[Pavel Machek]

[-- Attachment #1: Type: text/plain, Size: 401 bytes --]

On Wed 2019-07-10 14:39:30, Jean-Jacques Hiblot wrote:
> If the LED is acquired by a consumer device with devm_led_get(), it is
> automatically release when the device is detach.

released, detached.

Acked-by: Pavel Machek <pavel@ucw.cz>
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 3/4] dt-bindings: backlight: Add led-backlight binding

[Pavel Machek]

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On Wed 2019-07-10 14:39:31, Jean-Jacques Hiblot wrote:
> Add DT binding for led-backlight.
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
> ---
>  .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
>  1 file changed, 28 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> new file mode 100644
> index 000000000000..0444eec8efe1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> @@ -0,0 +1,28 @@
> +led-backlight bindings
> +
> +This binding is used to describe a basic backlight device made of
> LEDs.

Ok.

> +It can also be used to describe a backlight device controlled by the output of
> +a LED driver.

? The LED driver should better be driving some LEDs...

> +Required properties:
> +  - compatible: "led-backlight"
> +  - leds: a list of LEDs
> +
> +Optional properties:
> +  - brightness-levels: Array of distinct brightness levels. The levels must be
> +                       in the range accepted by the underlying LED devices.
> +                       This is used to translate a backlight brightness level
> +                       into a LED brightness level. if not provided, the
> +                       identity mapping is used.

"If it is not"
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 3/4] dt-bindings: backlight: Add led-backlight binding

[Pavel Machek]

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On Wed 2019-07-10 14:39:31, Jean-Jacques Hiblot wrote:
> Add DT binding for led-backlight.
> 
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
> ---
>  .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
>  1 file changed, 28 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> 
> diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> new file mode 100644
> index 000000000000..0444eec8efe1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> @@ -0,0 +1,28 @@
> +led-backlight bindings
> +
> +This binding is used to describe a basic backlight device made of
> LEDs.

Ok.

> +It can also be used to describe a backlight device controlled by the output of
> +a LED driver.

? The LED driver should better be driving some LEDs...

> +Required properties:
> +  - compatible: "led-backlight"
> +  - leds: a list of LEDs
> +
> +Optional properties:
> +  - brightness-levels: Array of distinct brightness levels. The levels must be
> +                       in the range accepted by the underlying LED devices.
> +                       This is used to translate a backlight brightness level
> +                       into a LED brightness level. if not provided, the
> +                       identity mapping is used.

"If it is not"
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 4/4] backlight: add led-backlight driver

[Pavel Machek]

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On Wed 2019-07-10 14:39:32, Jean-Jacques Hiblot wrote:
> From: Tomi Valkeinen <tomi.valkeinen@ti.com>
> 
> This patch adds a led-backlight driver (led_bl), which is similar to
> pwm_bl except the driver uses a LED class driver to adjust the
> brightness in the HW. Multiple LEDs can be used for a single backlight.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>

> +
> +		/*
> +		 *try to map actual LED brightness to backlight brightness
> +		 * level
> +		 */

"* Try"

> +		db = priv->default_brightness;
> +		for (i = 0 ; i < num_levels; i++) {
> +			if ((i && db > levels[i-1]) && db <= levels[i])
> +				break;
> +		}
> +		priv->default_brightness = i;
> +		priv->max_brightness = num_levels - 1;
> +		priv->levels = levels;
> +	} else if (num_levels >= 0)
> +		dev_warn(dev, "not enought levels defined\n");

"Not enough"

> +	ret = of_property_read_u32(node, "default-brightness-level", &value);
> +	if (!ret && value <= priv->max_brightness)
> +		priv->default_brightness = value;
> +	else if (!ret  && value > priv->max_brightness)
> +		dev_warn(dev, "invalid default brightness. ignoring it\n");

"Invalid... Ignoring it."

Acked-by: Pavel Machek <pavel@ucw.cz>
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 4/4] backlight: add led-backlight driver

[Pavel Machek]

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On Wed 2019-07-10 14:39:32, Jean-Jacques Hiblot wrote:
> From: Tomi Valkeinen <tomi.valkeinen@ti.com>
> 
> This patch adds a led-backlight driver (led_bl), which is similar to
> pwm_bl except the driver uses a LED class driver to adjust the
> brightness in the HW. Multiple LEDs can be used for a single backlight.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>

> +
> +		/*
> +		 *try to map actual LED brightness to backlight brightness
> +		 * level
> +		 */

"* Try"

> +		db = priv->default_brightness;
> +		for (i = 0 ; i < num_levels; i++) {
> +			if ((i && db > levels[i-1]) && db <= levels[i])
> +				break;
> +		}
> +		priv->default_brightness = i;
> +		priv->max_brightness = num_levels - 1;
> +		priv->levels = levels;
> +	} else if (num_levels >= 0)
> +		dev_warn(dev, "not enought levels defined\n");

"Not enough"

> +	ret = of_property_read_u32(node, "default-brightness-level", &value);
> +	if (!ret && value <= priv->max_brightness)
> +		priv->default_brightness = value;
> +	else if (!ret  && value > priv->max_brightness)
> +		dev_warn(dev, "invalid default brightness. ignoring it\n");

"Invalid... Ignoring it."

Acked-by: Pavel Machek <pavel@ucw.cz>
									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH v3 1/4] leds: Add of_led_get() and led_put()

[Jean-Jacques Hiblot]

hi Pavel

On 10/07/2019 21:09, Pavel Machek wrote:
> On Wed 2019-07-10 14:39:29, Jean-Jacques Hiblot wrote:
>> From: Tomi Valkeinen <tomi.valkeinen@ti.com>
>>
>> This patch adds basic support for a kernel driver to get a LED device.
>> This will be used by the led-backlight driver.
>>
>> Only OF version is implemented for now, and the behavior is similar to
>> PWM's of_pwm_get() and pwm_put().
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>>
>>
>> @@ -214,6 +215,55 @@ static int led_resume(struct device *dev)
>>   
>>   static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
>>   
>> +static int led_match_led_node(struct device *led_dev, const void *data)
>> +{
>> +	return led_dev->of_node == data ? 1 : 0;
>> +}
> Get rid of the "? 1 : 0"?
OK
>
>
>> +	led_node = of_parse_phandle(np, "leds", index);
>> +	if (!led_node)
>> +		return ERR_PTR(-ENOENT);
>> +	led_dev = class_find_device(leds_class, NULL, led_node,
>> +		led_match_led_node);
>> +	of_node_put(led_node);
>> +
>> +	if (!led_dev)
>> +		return ERR_PTR(-EPROBE_DEFER);
> Won't this defer probe "forever" when the driver is not available?

Yes it will.

However I don't see how we can fix this because we don't know for sure 
that the LED driver will not become available at a later time.

JJ



>
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Re: [PATCH v3 1/4] leds: Add of_led_get() and led_put()

[Jean-Jacques Hiblot]

hi Pavel

On 10/07/2019 21:09, Pavel Machek wrote:
> On Wed 2019-07-10 14:39:29, Jean-Jacques Hiblot wrote:
>> From: Tomi Valkeinen <tomi.valkeinen@ti.com>
>>
>> This patch adds basic support for a kernel driver to get a LED device.
>> This will be used by the led-backlight driver.
>>
>> Only OF version is implemented for now, and the behavior is similar to
>> PWM's of_pwm_get() and pwm_put().
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>>
>>
>> @@ -214,6 +215,55 @@ static int led_resume(struct device *dev)
>>   
>>   static SIMPLE_DEV_PM_OPS(leds_class_dev_pm_ops, led_suspend, led_resume);
>>   
>> +static int led_match_led_node(struct device *led_dev, const void *data)
>> +{
>> +	return led_dev->of_node == data ? 1 : 0;
>> +}
> Get rid of the "? 1 : 0"?
OK
>
>
>> +	led_node = of_parse_phandle(np, "leds", index);
>> +	if (!led_node)
>> +		return ERR_PTR(-ENOENT);
>> +	led_dev = class_find_device(leds_class, NULL, led_node,
>> +		led_match_led_node);
>> +	of_node_put(led_node);
>> +
>> +	if (!led_dev)
>> +		return ERR_PTR(-EPROBE_DEFER);
> Won't this defer probe "forever" when the driver is not available?

Yes it will.

However I don't see how we can fix this because we don't know for sure 
that the LED driver will not become available at a later time.

JJ



>

Re: [PATCH v3 3/4] dt-bindings: backlight: Add led-backlight binding

[Jean-Jacques Hiblot]

Pavel,

On 10/07/2019 21:13, Pavel Machek wrote:
> On Wed 2019-07-10 14:39:31, Jean-Jacques Hiblot wrote:
>> Add DT binding for led-backlight.
>>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>> ---
>>   .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
>>   1 file changed, 28 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
>>
>> diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
>> new file mode 100644
>> index 000000000000..0444eec8efe1
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
>> @@ -0,0 +1,28 @@
>> +led-backlight bindings
>> +
>> +This binding is used to describe a basic backlight device made of
>> LEDs.
> Ok.
>
>> +It can also be used to describe a backlight device controlled by the output of
>> +a LED driver.
> ? The LED driver should better be driving some LEDs...

Well. we are dependent of the board design. If a board designer decided 
to control a backlight with a LED-controller, then we have to deal with it.

In practice there are a lot of LED drivers that actually drive the LEDs 
using PWMs and can be used for this purpose.

JJ

>
>> +Required properties:
>> +  - compatible: "led-backlight"
>> +  - leds: a list of LEDs
>> +
>> +Optional properties:
>> +  - brightness-levels: Array of distinct brightness levels. The levels must be
>> +                       in the range accepted by the underlying LED devices.
>> +                       This is used to translate a backlight brightness level
>> +                       into a LED brightness level. if not provided, the
>> +                       identity mapping is used.
> "If it is not"
> 									Pavel
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: [PATCH v3 3/4] dt-bindings: backlight: Add led-backlight binding

[Jean-Jacques Hiblot]

Pavel,

On 10/07/2019 21:13, Pavel Machek wrote:
> On Wed 2019-07-10 14:39:31, Jean-Jacques Hiblot wrote:
>> Add DT binding for led-backlight.
>>
>> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>> ---
>>   .../bindings/leds/backlight/led-backlight.txt | 28 +++++++++++++++++++
>>   1 file changed, 28 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
>>
>> diff --git a/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
>> new file mode 100644
>> index 000000000000..0444eec8efe1
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
>> @@ -0,0 +1,28 @@
>> +led-backlight bindings
>> +
>> +This binding is used to describe a basic backlight device made of
>> LEDs.
> Ok.
>
>> +It can also be used to describe a backlight device controlled by the output of
>> +a LED driver.
> ? The LED driver should better be driving some LEDs...

Well. we are dependent of the board design. If a board designer decided 
to control a backlight with a LED-controller, then we have to deal with it.

In practice there are a lot of LED drivers that actually drive the LEDs 
using PWMs and can be used for this purpose.

JJ

>
>> +Required properties:
>> +  - compatible: "led-backlight"
>> +  - leds: a list of LEDs
>> +
>> +Optional properties:
>> +  - brightness-levels: Array of distinct brightness levels. The levels must be
>> +                       in the range accepted by the underlying LED devices.
>> +                       This is used to translate a backlight brightness level
>> +                       into a LED brightness level. if not provided, the
>> +                       identity mapping is used.
> "If it is not"
> 									Pavel