LED backlight on Droid 4 and others

LED backlight on Droid 4 and others

[Pavel Machek]

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Hi!

It would be good to get LED backlight to work in clean way for 5.6
kernel.

As far as I can see, these are neccessary (but not enough; it does not
work for me): lm3532 changes to register LED with of node, plus device
tree changes for droid 4, and these generic changes:

commit d457d0c97d6d55fe3e62633791ac05d289a37d2e
Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date:   Thu Oct 3 10:28:12 2019 +0200

    backlight: add led-backlight driver
    
    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>
    Acked-by: Pavel Machek <pavel@ucw.cz>
    Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

commit 44b7adbf0b07904e4198ae1d0a763917d1c68a23
Author: Jean-Jacques Hiblot <jjhiblot@ti.com>
Date:   Thu Oct 3 10:28:10 2019 +0200

    leds: Add managed API to get a LED from a device driver
    
    If the LED is acquired by a consumer device with devm_led_get(), it is
    automatically released when the device is detached.
    
    Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
    Acked-by: Pavel Machek <pavel@ucw.cz>
    Signed-off-by: Pavel <pavel@ucw.cz>

commit 93b98c570d7f898063ab6204e1b3950a3335dd12
Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date:   Thu Oct 3 10:28:09 2019 +0200

    leds: Add of_led_get() and led_put()
    
    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>
    Acked-by: Pavel Machek <pavel@ucw.cz>
    Signed-off-by: Pavel <pavel@ucw.cz>

[If you have an idea what else is needed, it would be welcome; it
works for me in development tree but not in tree I'd like to
upstream.]

Lee, would you be willing to take "backlight: add led-backlight
driver"? Would it help if I got "leds: Add managed API to get a LED
from a device driver" and "leds: Add of_led_get() and led_put()" into
for_next tree of the LED subsystem?

It is kind of important as, well, phone without screen looks pretty
much dead, and same issue hits Droid 4 and Librem 5 phones at least...

Best regards,
									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: LED backlight on Droid 4 and others

[Tony Lindgren]

* Pavel Machek <pavel@ucw.cz> [200105 18:32]:
> Hi!
> 
> It would be good to get LED backlight to work in clean way for 5.6
> kernel.

I agree, this is badly needed for many devices.

> [If you have an idea what else is needed, it would be welcome; it
> works for me in development tree but not in tree I'd like to
> upstream.]

I have some version of these patches working with modified dts in my
droid4-pending-v5.4 branch git branch, maybe try to diff against that.

Regards,

Tony

Re: LED backlight on Droid 4 and others

[Pavel Machek]

Hi!

> > It would be good to get LED backlight to work in clean way for 5.6
> > kernel.
> 
> I agree, this is badly needed for many devices.
> 
> > [If you have an idea what else is needed, it would be welcome; it
> > works for me in development tree but not in tree I'd like to
> > upstream.]
> 
> I have some version of these patches working with modified dts in my
> droid4-pending-v5.4 branch git branch, maybe try to diff against that.

Thanks a lot. I was missing 7dc08cb9ac7baff1601f65f66c4c611f841abc64.

Best regards,
								Pavel
> 

Re: LED backlight on Droid 4 and others

[Pavel Machek]

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Hi!

> > It would be good to get LED backlight to work in clean way for 5.6
> > kernel.
> 
> I agree, this is badly needed for many devices.
> 
> > [If you have an idea what else is needed, it would be welcome; it
> > works for me in development tree but not in tree I'd like to
> > upstream.]
> 
> I have some version of these patches working with modified dts in my
> droid4-pending-v5.4 branch git branch, maybe try to diff against that.

So.. backlight now works for me, and I put the LED parts of the
patches to

gitolite.kernel.org:pub/scm/linux/kernel/git/pavel/linux-leds.git for-next

tree. [I guess I could try to sneak them into 5.5 if that helps.]

Could we somehow get this to the backlight tree?

commit d457d0c97d6d55fe3e62633791ac05d289a37d2e
Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date:   Thu Oct 3 10:28:12 2019 +0200

    backlight: add led-backlight driver

    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>
 Acked-by: Pavel Machek <pavel@ucw.cz>
 Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

Best regards,
								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: LED backlight on Droid 4 and others

[Lee Jones]

On Sun, 05 Jan 2020, Pavel Machek wrote:

> Hi!
> 
> It would be good to get LED backlight to work in clean way for 5.6
> kernel.
> 
> As far as I can see, these are neccessary (but not enough; it does not
> work for me): lm3532 changes to register LED with of node, plus device
> tree changes for droid 4, and these generic changes:
> 
> commit d457d0c97d6d55fe3e62633791ac05d289a37d2e
> Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Date:   Thu Oct 3 10:28:12 2019 +0200
> 
>     backlight: add led-backlight driver
>     
>     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>
>     Acked-by: Pavel Machek <pavel@ucw.cz>
>     Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> 
> commit 44b7adbf0b07904e4198ae1d0a763917d1c68a23
> Author: Jean-Jacques Hiblot <jjhiblot@ti.com>
> Date:   Thu Oct 3 10:28:10 2019 +0200
> 
>     leds: Add managed API to get a LED from a device driver
>     
>     If the LED is acquired by a consumer device with devm_led_get(), it is
>     automatically released when the device is detached.
>     
>     Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
>     Acked-by: Pavel Machek <pavel@ucw.cz>
>     Signed-off-by: Pavel <pavel@ucw.cz>
> 
> commit 93b98c570d7f898063ab6204e1b3950a3335dd12
> Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Date:   Thu Oct 3 10:28:09 2019 +0200
> 
>     leds: Add of_led_get() and led_put()
>     
>     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>
>     Acked-by: Pavel Machek <pavel@ucw.cz>
>     Signed-off-by: Pavel <pavel@ucw.cz>
> 
> [If you have an idea what else is needed, it would be welcome; it
> works for me in development tree but not in tree I'd like to
> upstream.]
> 
> Lee, would you be willing to take "backlight: add led-backlight
> driver"? Would it help if I got "leds: Add managed API to get a LED
> from a device driver" and "leds: Add of_led_get() and led_put()" into
> for_next tree of the LED subsystem?

It looks like you have an open question from Tony on v10.

Is that patch orthogonal, or are there depend{ants,encies}?

> It is kind of important as, well, phone without screen looks pretty
> much dead, and same issue hits Droid 4 and Librem 5 phones at least...
> 
> Best regards,
> 									Pavel



-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: LED backlight on Droid 4 and others

[Tony Lindgren]

* Lee Jones <lee.jones@linaro.org> [200106 08:46]:
> On Sun, 05 Jan 2020, Pavel Machek wrote:
> 
> > Hi!
> > 
> > It would be good to get LED backlight to work in clean way for 5.6
> > kernel.
...
> > [If you have an idea what else is needed, it would be welcome; it
> > works for me in development tree but not in tree I'd like to
> > upstream.]
> > 
> > Lee, would you be willing to take "backlight: add led-backlight
> > driver"? Would it help if I got "leds: Add managed API to get a LED
> > from a device driver" and "leds: Add of_led_get() and led_put()" into
> > for_next tree of the LED subsystem?
> 
> It looks like you have an open question from Tony on v10.
> 
> Is that patch orthogonal, or are there depend{ants,encies}?

Uhh looks like we messed up a bit with integration. Now droid4
LCD backlight can no longer be enabled at all manually in v5.6-rc1
without the "add led-backlight driver" patch.. Should we just
merge it to fix it rather than start scrambling with other
temporary hacks?

I don't care if we use "default-brightness", or if we use
"default-brightness-level". The binding merged says now
"default-brightness", so let's go with that one. That's what
other LED drivers are using too.

Regards,

Tony

Re: LED backlight on Droid 4 and others

[Pavel Machek]

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Hi!

> > > It would be good to get LED backlight to work in clean way for 5.6
> > > kernel.
> ...
> > > [If you have an idea what else is needed, it would be welcome; it
> > > works for me in development tree but not in tree I'd like to
> > > upstream.]
> > > 
> > > Lee, would you be willing to take "backlight: add led-backlight
> > > driver"? Would it help if I got "leds: Add managed API to get a LED
> > > from a device driver" and "leds: Add of_led_get() and led_put()" into
> > > for_next tree of the LED subsystem?
> > 
> > It looks like you have an open question from Tony on v10.
> > 
> > Is that patch orthogonal, or are there depend{ants,encies}?
> 
> Uhh looks like we messed up a bit with integration. Now droid4
> LCD backlight can no longer be enabled at all manually in v5.6-rc1
> without the "add led-backlight driver" patch.. Should we just
> merge it to fix it rather than start scrambling with other
> temporary hacks?

We should just merge the "add led-backlight driver". Everything should
be ready for it. I'm sorry if I broke something working, I was not
aware it worked at all.

Unfortunately, this is backlight code, not LED, so I can't just merge it.

> I don't care if we use "default-brightness", or if we use
> "default-brightness-level". The binding merged says now
> "default-brightness", so let's go with that one. That's what
> other LED drivers are using too.

No opinion on that.

Best regards,
									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: LED backlight on Droid 4 and others

[Lee Jones]

On Wed, 12 Feb 2020, Pavel Machek wrote:

> Hi!
> 
> > > > It would be good to get LED backlight to work in clean way for 5.6
> > > > kernel.
> > ...
> > > > [If you have an idea what else is needed, it would be welcome; it
> > > > works for me in development tree but not in tree I'd like to
> > > > upstream.]
> > > > 
> > > > Lee, would you be willing to take "backlight: add led-backlight
> > > > driver"? Would it help if I got "leds: Add managed API to get a LED
> > > > from a device driver" and "leds: Add of_led_get() and led_put()" into
> > > > for_next tree of the LED subsystem?
> > > 
> > > It looks like you have an open question from Tony on v10.
> > > 
> > > Is that patch orthogonal, or are there depend{ants,encies}?
> > 
> > Uhh looks like we messed up a bit with integration. Now droid4
> > LCD backlight can no longer be enabled at all manually in v5.6-rc1
> > without the "add led-backlight driver" patch.. Should we just
> > merge it to fix it rather than start scrambling with other
> > temporary hacks?
> 
> We should just merge the "add led-backlight driver". Everything should
> be ready for it. I'm sorry if I broke something working, I was not
> aware it worked at all.
> 
> Unfortunately, this is backlight code, not LED, so I can't just merge it.

Please go ahead.  Apply my Acked-by and merge away ASAP.

Acked-by: Lee Jones <lee.jones@linaro.org>

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: LED backlight on Droid 4 and others

[Tony Lindgren]

* Lee Jones <lee.jones@linaro.org> [200218 13:52]:
> On Wed, 12 Feb 2020, Pavel Machek wrote:
> 
> > Hi!
> > 
> > > > > It would be good to get LED backlight to work in clean way for 5.6
> > > > > kernel.
> > > ...
> > > > > [If you have an idea what else is needed, it would be welcome; it
> > > > > works for me in development tree but not in tree I'd like to
> > > > > upstream.]
> > > > > 
> > > > > Lee, would you be willing to take "backlight: add led-backlight
> > > > > driver"? Would it help if I got "leds: Add managed API to get a LED
> > > > > from a device driver" and "leds: Add of_led_get() and led_put()" into
> > > > > for_next tree of the LED subsystem?
> > > > 
> > > > It looks like you have an open question from Tony on v10.
> > > > 
> > > > Is that patch orthogonal, or are there depend{ants,encies}?
> > > 
> > > Uhh looks like we messed up a bit with integration. Now droid4
> > > LCD backlight can no longer be enabled at all manually in v5.6-rc1
> > > without the "add led-backlight driver" patch.. Should we just
> > > merge it to fix it rather than start scrambling with other
> > > temporary hacks?
> > 
> > We should just merge the "add led-backlight driver". Everything should
> > be ready for it. I'm sorry if I broke something working, I was not
> > aware it worked at all.
> > 
> > Unfortunately, this is backlight code, not LED, so I can't just merge it.
> 
> Please go ahead.  Apply my Acked-by and merge away ASAP.
> 
> Acked-by: Lee Jones <lee.jones@linaro.org>

OK best to merge the driver via the LED tree:

Acked-by: Tony Lindgren <tony@atomide.com>
Tested-by: Tony Lindgren <tony@atomide.com>

Re: LED backlight on Droid 4 and others

[Pavel Machek]

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Hi!

> > > > > > It would be good to get LED backlight to work in clean way for 5.6
> > > > > > kernel.
> > > > ...
> > > > > > [If you have an idea what else is needed, it would be welcome; it
> > > > > > works for me in development tree but not in tree I'd like to
> > > > > > upstream.]
> > > > > > 
> > > > > > Lee, would you be willing to take "backlight: add led-backlight
> > > > > > driver"? Would it help if I got "leds: Add managed API to get a LED
> > > > > > from a device driver" and "leds: Add of_led_get() and led_put()" into
> > > > > > for_next tree of the LED subsystem?
> > > > > 
> > > > > It looks like you have an open question from Tony on v10.
> > > > > 
> > > > > Is that patch orthogonal, or are there depend{ants,encies}?
> > > > 
> > > > Uhh looks like we messed up a bit with integration. Now droid4
> > > > LCD backlight can no longer be enabled at all manually in v5.6-rc1
> > > > without the "add led-backlight driver" patch.. Should we just
> > > > merge it to fix it rather than start scrambling with other
> > > > temporary hacks?
> > > 
> > > We should just merge the "add led-backlight driver". Everything should
> > > be ready for it. I'm sorry if I broke something working, I was not
> > > aware it worked at all.
> > > 
> > > Unfortunately, this is backlight code, not LED, so I can't just merge it.
> > 
> > Please go ahead.  Apply my Acked-by and merge away ASAP.
> > 
> > Acked-by: Lee Jones <lee.jones@linaro.org>
> 
> OK best to merge the driver via the LED tree:
> 
> Acked-by: Tony Lindgren <tony@atomide.com>
> Tested-by: Tony Lindgren <tony@atomide.com>

Is the patch below the one both of you are talking about?

Hmm. I should s/default-brightness-level/default-brightness/
below.

Lee, I can of course take it (thanks), but won't Kconfig/Makefile
pieces cause rejects? It might be still better if you took it. I can
hand-edit it and submit it in form for easy application... tommorow.

Best regards,

									Pavel

commit 81a2daadf8dd6c8e0cbc3b60246932436be3c714
Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
Date:   Thu Oct 3 10:28:12 2019 +0200

    backlight: add led-backlight driver
    
    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>
    Acked-by: Pavel Machek <pavel@ucw.cz>
    Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>

diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index 4c8f73394aac..93836ef872f5 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -463,6 +463,13 @@ 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 961fb553b9c0..5e13242f31d6 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -60,3 +60,4 @@ 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..3f66549997c8
--- /dev/null
+++ b/drivers/video/backlight/led_bl.c
@@ -0,0 +1,260 @@
+// 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/leds.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+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 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++)
+		led_set_brightness(priv->leds[i], bkl_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_of_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 enough 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, i;
+
+	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);
+	}
+
+	for (i = 0; i < priv->nb_leds; i++)
+		led_sysfs_disable(priv->leds[i]);
+
+	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;
+	int i;
+
+	backlight_device_unregister(bl);
+
+	led_bl_power_off(priv);
+	for (i = 0; i < priv->nb_leds; i++)
+		led_sysfs_enable(priv->leds[i]);
+
+	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");

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

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 181 bytes --]

Re: LED backlight on Droid 4 and others

[Lee Jones]

On Wed, 19 Feb 2020, Pavel Machek wrote:

> Hi!
> 
> > > > > > > It would be good to get LED backlight to work in clean way for 5.6
> > > > > > > kernel.
> > > > > ...
> > > > > > > [If you have an idea what else is needed, it would be welcome; it
> > > > > > > works for me in development tree but not in tree I'd like to
> > > > > > > upstream.]
> > > > > > > 
> > > > > > > Lee, would you be willing to take "backlight: add led-backlight
> > > > > > > driver"? Would it help if I got "leds: Add managed API to get a LED
> > > > > > > from a device driver" and "leds: Add of_led_get() and led_put()" into
> > > > > > > for_next tree of the LED subsystem?
> > > > > > 
> > > > > > It looks like you have an open question from Tony on v10.
> > > > > > 
> > > > > > Is that patch orthogonal, or are there depend{ants,encies}?
> > > > > 
> > > > > Uhh looks like we messed up a bit with integration. Now droid4
> > > > > LCD backlight can no longer be enabled at all manually in v5.6-rc1
> > > > > without the "add led-backlight driver" patch.. Should we just
> > > > > merge it to fix it rather than start scrambling with other
> > > > > temporary hacks?
> > > > 
> > > > We should just merge the "add led-backlight driver". Everything should
> > > > be ready for it. I'm sorry if I broke something working, I was not
> > > > aware it worked at all.
> > > > 
> > > > Unfortunately, this is backlight code, not LED, so I can't just merge it.
> > > 
> > > Please go ahead.  Apply my Acked-by and merge away ASAP.
> > > 
> > > Acked-by: Lee Jones <lee.jones@linaro.org>
> > 
> > OK best to merge the driver via the LED tree:
> > 
> > Acked-by: Tony Lindgren <tony@atomide.com>
> > Tested-by: Tony Lindgren <tony@atomide.com>
> 
> Is the patch below the one both of you are talking about?
> 
> Hmm. I should s/default-brightness-level/default-brightness/
> below.
> 
> Lee, I can of course take it (thanks), but won't Kconfig/Makefile
> pieces cause rejects? It might be still better if you took it. I can
> hand-edit it and submit it in form for easy application... tommorow.

My suggestion would be to send it to Linus ASAP.

Ideally it would get into the -rcs, as it 'fixes' things.

> Best regards,
> 
> 									Pavel
> 
> commit 81a2daadf8dd6c8e0cbc3b60246932436be3c714
> Author: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Date:   Thu Oct 3 10:28:12 2019 +0200
> 
>     backlight: add led-backlight driver
>     
>     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>
>     Acked-by: Pavel Machek <pavel@ucw.cz>
>     Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> 
> diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
> index 4c8f73394aac..93836ef872f5 100644
> --- a/drivers/video/backlight/Kconfig
> +++ b/drivers/video/backlight/Kconfig
> @@ -463,6 +463,13 @@ 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 961fb553b9c0..5e13242f31d6 100644
> --- a/drivers/video/backlight/Makefile
> +++ b/drivers/video/backlight/Makefile
> @@ -60,3 +60,4 @@ 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..3f66549997c8
> --- /dev/null
> +++ b/drivers/video/backlight/led_bl.c
> @@ -0,0 +1,260 @@
> +// 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/leds.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +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 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++)
> +		led_set_brightness(priv->leds[i], bkl_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_of_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 enough 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, i;
> +
> +	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);
> +	}
> +
> +	for (i = 0; i < priv->nb_leds; i++)
> +		led_sysfs_disable(priv->leds[i]);
> +
> +	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;
> +	int i;
> +
> +	backlight_device_unregister(bl);
> +
> +	led_bl_power_off(priv);
> +	for (i = 0; i < priv->nb_leds; i++)
> +		led_sysfs_enable(priv->leds[i]);
> +
> +	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");
> 



-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: LED backlight on Droid 4 and others

[Tony Lindgren]

* Lee Jones <lee.jones@linaro.org> [200219 07:47]:
> On Wed, 19 Feb 2020, Pavel Machek wrote:
> 
> > Hi!
> > 
> > > > > > > > It would be good to get LED backlight to work in clean way for 5.6
> > > > > > > > kernel.
> > > > > > ...
> > > > > > > > [If you have an idea what else is needed, it would be welcome; it
> > > > > > > > works for me in development tree but not in tree I'd like to
> > > > > > > > upstream.]
> > > > > > > > 
> > > > > > > > Lee, would you be willing to take "backlight: add led-backlight
> > > > > > > > driver"? Would it help if I got "leds: Add managed API to get a LED
> > > > > > > > from a device driver" and "leds: Add of_led_get() and led_put()" into
> > > > > > > > for_next tree of the LED subsystem?
> > > > > > > 
> > > > > > > It looks like you have an open question from Tony on v10.
> > > > > > > 
> > > > > > > Is that patch orthogonal, or are there depend{ants,encies}?
> > > > > > 
> > > > > > Uhh looks like we messed up a bit with integration. Now droid4
> > > > > > LCD backlight can no longer be enabled at all manually in v5.6-rc1
> > > > > > without the "add led-backlight driver" patch.. Should we just
> > > > > > merge it to fix it rather than start scrambling with other
> > > > > > temporary hacks?
> > > > > 
> > > > > We should just merge the "add led-backlight driver". Everything should
> > > > > be ready for it. I'm sorry if I broke something working, I was not
> > > > > aware it worked at all.
> > > > > 
> > > > > Unfortunately, this is backlight code, not LED, so I can't just merge it.
> > > > 
> > > > Please go ahead.  Apply my Acked-by and merge away ASAP.
> > > > 
> > > > Acked-by: Lee Jones <lee.jones@linaro.org>
> > > 
> > > OK best to merge the driver via the LED tree:
> > > 
> > > Acked-by: Tony Lindgren <tony@atomide.com>
> > > Tested-by: Tony Lindgren <tony@atomide.com>
> > 
> > Is the patch below the one both of you are talking about?
> > 
> > Hmm. I should s/default-brightness-level/default-brightness/
> > below.
> > 
> > Lee, I can of course take it (thanks), but won't Kconfig/Makefile
> > pieces cause rejects? It might be still better if you took it. I can
> > hand-edit it and submit it in form for easy application... tommorow.
> 
> My suggestion would be to send it to Linus ASAP.
> 
> Ideally it would get into the -rcs, as it 'fixes' things.

I agree. Pavel, the version of the patch you posted is all space
trashed. Can you please post again so I can verify the related dts
changes against it?

Regards,

Tony