Re: [PATCH 1/1 v2] pwm_bl: Add support for backlight enable GPIO
On Mon, Mar 04, 2013 at 08:43:50PM -0800, Andrew Chew wrote: > The backlight enable GPIO is specified in the device tree node for > backlight. > > Signed-off-by: Andrew Chew > --- > I decided to go ahead with disabling/enabling the backlight via GPIO as > needed. Note that I named the new functions pwm_backlight_enable() and > pwm_backlight_disable() (instead of something more gpio-specific) because > I thought it would be convenient to have a generic hook for when someone > wants to add yet more stuff to be done on enable/disable. > > I tested this by going into /sys/class/backlight/backlight.n and manually > adjusting the brightness, and checked the gpio state to see that it had > the appropriate value. > > .../bindings/video/backlight/pwm-backlight.txt |2 + > drivers/video/backlight/pwm_bl.c | 50 > ++-- > include/linux/pwm_backlight.h |2 + > 3 files changed, 50 insertions(+), 4 deletions(-) > > diff --git > a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > index 1e4fc72..1ed4f0f 100644 > --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt > @@ -14,6 +14,8 @@ Required properties: > Optional properties: >- pwm-names: a list of names for the PWM devices specified in the > "pwms" property (see PWM binding[0]) > + - enable-gpio: a GPIO that needs to be used to enable the backlight According to Documentation/devicetree/bindings/gpio/gpio.txt this should be called "enable-gpios". > + - enable-gpio-active-high: polarity of GPIO is active high (default is low) There is OF_GPIO_ACTIVE_LOW, which is automatically parsed from the second cell of a GPIO specifier. It will only work if you request the GPIO using of_get_named_gpio_flags(), though, so it will only work in the non-DT case. I think using a regulator would be more appropriate, since it gives you more flexibility than a plain GPIO. Does anybody see a problem with using a regulator instead? Thierry pgpOelTVTf4Oe.pgp Description: PGP signature
Re: [PATCH 1/1 v2] pwm_bl: Add support for backlight enable GPIO
On 03/05/2013 01:43 PM, Andrew Chew wrote:
The backlight enable GPIO is specified in the device tree node for
backlight.
Signed-off-by: Andrew Chew
---
I decided to go ahead with disabling/enabling the backlight via GPIO as
needed. Note that I named the new functions pwm_backlight_enable() and
pwm_backlight_disable() (instead of something more gpio-specific) because
I thought it would be convenient to have a generic hook for when someone
wants to add yet more stuff to be done on enable/disable.
I tested this by going into /sys/class/backlight/backlight.n and manually
adjusting the brightness, and checked the gpio state to see that it had
the appropriate value.
.../bindings/video/backlight/pwm-backlight.txt |2 +
drivers/video/backlight/pwm_bl.c | 50 ++--
include/linux/pwm_backlight.h |2 +
3 files changed, 50 insertions(+), 4 deletions(-)
diff --git
a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..1ed4f0f 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,6 +14,8 @@ Required properties:
Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
"pwms" property (see PWM binding[0])
+ - enable-gpio: a GPIO that needs to be used to enable the backlight
+ - enable-gpio-active-high: polarity of GPIO is active high (default is low)
[0]: Documentation/devicetree/bindings/pwm/pwm.txt
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 069983c..7dd426e 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -20,10 +20,13 @@
#include
#include
#include
+#include
struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
+ int enable_gpio;
+ unsigned intenable_gpio_flags;
unsigned intperiod;
unsigned intlth_brightness;
unsigned int*levels;
@@ -35,6 +38,20 @@ struct pwm_bl_data {
void(*exit)(struct device *);
};
+static void pwm_backlight_enable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb->enable_gpio))
+ gpio_set_value(pb->enable_gpio,
+ pb->enable_gpio_flags & GPIOF_INIT_HIGH ? 1 : 0);
+}
+
+static void pwm_backlight_disable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb->enable_gpio))
+ gpio_set_value(pb->enable_gpio,
+ pb->enable_gpio_flags & GPIOF_INIT_HIGH ? 0 : 1);
+}
+
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(>dev);
@@ -53,6 +70,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
if (brightness == 0) {
pwm_config(pb->pwm, 0, pb->period);
pwm_disable(pb->pwm);
+ pwm_backlight_disable(pb);
Maybe move the call to pwm_backlight_disable() before pwm_disable() to
have a correctly nested power sequence?
Actually every call to pwm_disable/enable is near
pwm_backlight_disable/enable, so you might as well want to call
pwm_disable/enable within pwm_backlight_enable/disable to make the code
more bullet-proof.
} else {
int duty_cycle;
@@ -67,6 +85,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
(duty_cycle * (pb->period - pb->lth_brightness) / max);
pwm_config(pb->pwm, duty_cycle, pb->period);
pwm_enable(pb->pwm);
+ pwm_backlight_enable(pb);
}
if (pb->notify_after)
@@ -146,10 +165,15 @@ static int pwm_backlight_parse_dt(struct device *dev,
}
/*
-* TODO: Most users of this driver use a number of GPIOs to control
-* backlight power. Support for specifying these needs to be
-* added.
+* If "enable-gpio" is present, use that GPIO to enable the backlight.
+* The presence (or not) of "enable-gpio-active-high" will determine
+* the value of the GPIO.
*/
+ data->enable_gpio = of_get_named_gpio(node, "enable-gpio", 0);
+ if (of_property_read_bool(node, "enable-gpio-active-high"))
+ data->enable_gpio_flags = GPIOF_OUT_INIT_HIGH;
+ else
+ data->enable_gpio_flags = GPIOF_OUT_INIT_LOW;
return 0;
}
@@ -207,12 +231,23 @@ static int pwm_backlight_probe(struct platform_device
*pdev)
} else
max = data->max_brightness;
+ pb->enable_gpio = data->enable_gpio;
+ pb->enable_gpio_flags = data->enable_gpio_flags;
pb->notify = data->notify;
[PATCH 1/1 v2] pwm_bl: Add support for backlight enable GPIO
The backlight enable GPIO is specified in the device tree node for
backlight.
Signed-off-by: Andrew Chew
---
I decided to go ahead with disabling/enabling the backlight via GPIO as
needed. Note that I named the new functions pwm_backlight_enable() and
pwm_backlight_disable() (instead of something more gpio-specific) because
I thought it would be convenient to have a generic hook for when someone
wants to add yet more stuff to be done on enable/disable.
I tested this by going into /sys/class/backlight/backlight.n and manually
adjusting the brightness, and checked the gpio state to see that it had
the appropriate value.
.../bindings/video/backlight/pwm-backlight.txt |2 +
drivers/video/backlight/pwm_bl.c | 50 ++--
include/linux/pwm_backlight.h |2 +
3 files changed, 50 insertions(+), 4 deletions(-)
diff --git
a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..1ed4f0f 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,6 +14,8 @@ Required properties:
Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
"pwms" property (see PWM binding[0])
+ - enable-gpio: a GPIO that needs to be used to enable the backlight
+ - enable-gpio-active-high: polarity of GPIO is active high (default is low)
[0]: Documentation/devicetree/bindings/pwm/pwm.txt
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 069983c..7dd426e 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -20,10 +20,13 @@
#include
#include
#include
+#include
struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
+ int enable_gpio;
+ unsigned intenable_gpio_flags;
unsigned intperiod;
unsigned intlth_brightness;
unsigned int*levels;
@@ -35,6 +38,20 @@ struct pwm_bl_data {
void(*exit)(struct device *);
};
+static void pwm_backlight_enable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb->enable_gpio))
+ gpio_set_value(pb->enable_gpio,
+ pb->enable_gpio_flags & GPIOF_INIT_HIGH ? 1 : 0);
+}
+
+static void pwm_backlight_disable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb->enable_gpio))
+ gpio_set_value(pb->enable_gpio,
+ pb->enable_gpio_flags & GPIOF_INIT_HIGH ? 0 : 1);
+}
+
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(>dev);
@@ -53,6 +70,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
if (brightness == 0) {
pwm_config(pb->pwm, 0, pb->period);
pwm_disable(pb->pwm);
+ pwm_backlight_disable(pb);
} else {
int duty_cycle;
@@ -67,6 +85,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
(duty_cycle * (pb->period - pb->lth_brightness) / max);
pwm_config(pb->pwm, duty_cycle, pb->period);
pwm_enable(pb->pwm);
+ pwm_backlight_enable(pb);
}
if (pb->notify_after)
@@ -146,10 +165,15 @@ static int pwm_backlight_parse_dt(struct device *dev,
}
/*
-* TODO: Most users of this driver use a number of GPIOs to control
-* backlight power. Support for specifying these needs to be
-* added.
+* If "enable-gpio" is present, use that GPIO to enable the backlight.
+* The presence (or not) of "enable-gpio-active-high" will determine
+* the value of the GPIO.
*/
+ data->enable_gpio = of_get_named_gpio(node, "enable-gpio", 0);
+ if (of_property_read_bool(node, "enable-gpio-active-high"))
+ data->enable_gpio_flags = GPIOF_OUT_INIT_HIGH;
+ else
+ data->enable_gpio_flags = GPIOF_OUT_INIT_LOW;
return 0;
}
@@ -207,12 +231,23 @@ static int pwm_backlight_probe(struct platform_device
*pdev)
} else
max = data->max_brightness;
+ pb->enable_gpio = data->enable_gpio;
+ pb->enable_gpio_flags = data->enable_gpio_flags;
pb->notify = data->notify;
pb->notify_after = data->notify_after;
pb->check_fb = data->check_fb;
pb->exit = data->exit;
pb->dev = >dev;
+ if (gpio_is_valid(pb->enable_gpio)) {
+ ret = gpio_request_one(pb->enable_gpio,
+ GPIOF_DIR_OUT | pb->enable_gpio_flags, "bl_en");
+ if (ret) {
+ dev_err(>dev, "failed to
[PATCH 1/1 v2] pwm_bl: Add support for backlight enable GPIO
The backlight enable GPIO is specified in the device tree node for
backlight.
Signed-off-by: Andrew Chew ac...@nvidia.com
---
I decided to go ahead with disabling/enabling the backlight via GPIO as
needed. Note that I named the new functions pwm_backlight_enable() and
pwm_backlight_disable() (instead of something more gpio-specific) because
I thought it would be convenient to have a generic hook for when someone
wants to add yet more stuff to be done on enable/disable.
I tested this by going into /sys/class/backlight/backlight.n and manually
adjusting the brightness, and checked the gpio state to see that it had
the appropriate value.
.../bindings/video/backlight/pwm-backlight.txt |2 +
drivers/video/backlight/pwm_bl.c | 50 ++--
include/linux/pwm_backlight.h |2 +
3 files changed, 50 insertions(+), 4 deletions(-)
diff --git
a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..1ed4f0f 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,6 +14,8 @@ Required properties:
Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
pwms property (see PWM binding[0])
+ - enable-gpio: a GPIO that needs to be used to enable the backlight
+ - enable-gpio-active-high: polarity of GPIO is active high (default is low)
[0]: Documentation/devicetree/bindings/pwm/pwm.txt
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 069983c..7dd426e 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -20,10 +20,13 @@
#include linux/pwm.h
#include linux/pwm_backlight.h
#include linux/slab.h
+#include linux/of_gpio.h
struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
+ int enable_gpio;
+ unsigned intenable_gpio_flags;
unsigned intperiod;
unsigned intlth_brightness;
unsigned int*levels;
@@ -35,6 +38,20 @@ struct pwm_bl_data {
void(*exit)(struct device *);
};
+static void pwm_backlight_enable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb-enable_gpio))
+ gpio_set_value(pb-enable_gpio,
+ pb-enable_gpio_flags GPIOF_INIT_HIGH ? 1 : 0);
+}
+
+static void pwm_backlight_disable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb-enable_gpio))
+ gpio_set_value(pb-enable_gpio,
+ pb-enable_gpio_flags GPIOF_INIT_HIGH ? 0 : 1);
+}
+
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(bl-dev);
@@ -53,6 +70,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
if (brightness == 0) {
pwm_config(pb-pwm, 0, pb-period);
pwm_disable(pb-pwm);
+ pwm_backlight_disable(pb);
} else {
int duty_cycle;
@@ -67,6 +85,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
(duty_cycle * (pb-period - pb-lth_brightness) / max);
pwm_config(pb-pwm, duty_cycle, pb-period);
pwm_enable(pb-pwm);
+ pwm_backlight_enable(pb);
}
if (pb-notify_after)
@@ -146,10 +165,15 @@ static int pwm_backlight_parse_dt(struct device *dev,
}
/*
-* TODO: Most users of this driver use a number of GPIOs to control
-* backlight power. Support for specifying these needs to be
-* added.
+* If enable-gpio is present, use that GPIO to enable the backlight.
+* The presence (or not) of enable-gpio-active-high will determine
+* the value of the GPIO.
*/
+ data-enable_gpio = of_get_named_gpio(node, enable-gpio, 0);
+ if (of_property_read_bool(node, enable-gpio-active-high))
+ data-enable_gpio_flags = GPIOF_OUT_INIT_HIGH;
+ else
+ data-enable_gpio_flags = GPIOF_OUT_INIT_LOW;
return 0;
}
@@ -207,12 +231,23 @@ static int pwm_backlight_probe(struct platform_device
*pdev)
} else
max = data-max_brightness;
+ pb-enable_gpio = data-enable_gpio;
+ pb-enable_gpio_flags = data-enable_gpio_flags;
pb-notify = data-notify;
pb-notify_after = data-notify_after;
pb-check_fb = data-check_fb;
pb-exit = data-exit;
pb-dev = pdev-dev;
+ if (gpio_is_valid(pb-enable_gpio)) {
+ ret = gpio_request_one(pb-enable_gpio,
+ GPIOF_DIR_OUT | pb-enable_gpio_flags, bl_en);
+ if (ret) {
+
Re: [PATCH 1/1 v2] pwm_bl: Add support for backlight enable GPIO
On 03/05/2013 01:43 PM, Andrew Chew wrote:
The backlight enable GPIO is specified in the device tree node for
backlight.
Signed-off-by: Andrew Chew ac...@nvidia.com
---
I decided to go ahead with disabling/enabling the backlight via GPIO as
needed. Note that I named the new functions pwm_backlight_enable() and
pwm_backlight_disable() (instead of something more gpio-specific) because
I thought it would be convenient to have a generic hook for when someone
wants to add yet more stuff to be done on enable/disable.
I tested this by going into /sys/class/backlight/backlight.n and manually
adjusting the brightness, and checked the gpio state to see that it had
the appropriate value.
.../bindings/video/backlight/pwm-backlight.txt |2 +
drivers/video/backlight/pwm_bl.c | 50 ++--
include/linux/pwm_backlight.h |2 +
3 files changed, 50 insertions(+), 4 deletions(-)
diff --git
a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..1ed4f0f 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -14,6 +14,8 @@ Required properties:
Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
pwms property (see PWM binding[0])
+ - enable-gpio: a GPIO that needs to be used to enable the backlight
+ - enable-gpio-active-high: polarity of GPIO is active high (default is low)
[0]: Documentation/devicetree/bindings/pwm/pwm.txt
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 069983c..7dd426e 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -20,10 +20,13 @@
#include linux/pwm.h
#include linux/pwm_backlight.h
#include linux/slab.h
+#include linux/of_gpio.h
struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
+ int enable_gpio;
+ unsigned intenable_gpio_flags;
unsigned intperiod;
unsigned intlth_brightness;
unsigned int*levels;
@@ -35,6 +38,20 @@ struct pwm_bl_data {
void(*exit)(struct device *);
};
+static void pwm_backlight_enable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb-enable_gpio))
+ gpio_set_value(pb-enable_gpio,
+ pb-enable_gpio_flags GPIOF_INIT_HIGH ? 1 : 0);
+}
+
+static void pwm_backlight_disable(struct pwm_bl_data *pb)
+{
+ if (gpio_is_valid(pb-enable_gpio))
+ gpio_set_value(pb-enable_gpio,
+ pb-enable_gpio_flags GPIOF_INIT_HIGH ? 0 : 1);
+}
+
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(bl-dev);
@@ -53,6 +70,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
if (brightness == 0) {
pwm_config(pb-pwm, 0, pb-period);
pwm_disable(pb-pwm);
+ pwm_backlight_disable(pb);
Maybe move the call to pwm_backlight_disable() before pwm_disable() to
have a correctly nested power sequence?
Actually every call to pwm_disable/enable is near
pwm_backlight_disable/enable, so you might as well want to call
pwm_disable/enable within pwm_backlight_enable/disable to make the code
more bullet-proof.
} else {
int duty_cycle;
@@ -67,6 +85,7 @@ static int pwm_backlight_update_status(struct
backlight_device *bl)
(duty_cycle * (pb-period - pb-lth_brightness) / max);
pwm_config(pb-pwm, duty_cycle, pb-period);
pwm_enable(pb-pwm);
+ pwm_backlight_enable(pb);
}
if (pb-notify_after)
@@ -146,10 +165,15 @@ static int pwm_backlight_parse_dt(struct device *dev,
}
/*
-* TODO: Most users of this driver use a number of GPIOs to control
-* backlight power. Support for specifying these needs to be
-* added.
+* If enable-gpio is present, use that GPIO to enable the backlight.
+* The presence (or not) of enable-gpio-active-high will determine
+* the value of the GPIO.
*/
+ data-enable_gpio = of_get_named_gpio(node, enable-gpio, 0);
+ if (of_property_read_bool(node, enable-gpio-active-high))
+ data-enable_gpio_flags = GPIOF_OUT_INIT_HIGH;
+ else
+ data-enable_gpio_flags = GPIOF_OUT_INIT_LOW;
return 0;
}
@@ -207,12 +231,23 @@ static int pwm_backlight_probe(struct platform_device
*pdev)
} else
max = data-max_brightness;
+ pb-enable_gpio = data-enable_gpio;
+ pb-enable_gpio_flags = data-enable_gpio_flags;
Re: [PATCH 1/1 v2] pwm_bl: Add support for backlight enable GPIO
On Mon, Mar 04, 2013 at 08:43:50PM -0800, Andrew Chew wrote: The backlight enable GPIO is specified in the device tree node for backlight. Signed-off-by: Andrew Chew ac...@nvidia.com --- I decided to go ahead with disabling/enabling the backlight via GPIO as needed. Note that I named the new functions pwm_backlight_enable() and pwm_backlight_disable() (instead of something more gpio-specific) because I thought it would be convenient to have a generic hook for when someone wants to add yet more stuff to be done on enable/disable. I tested this by going into /sys/class/backlight/backlight.n and manually adjusting the brightness, and checked the gpio state to see that it had the appropriate value. .../bindings/video/backlight/pwm-backlight.txt |2 + drivers/video/backlight/pwm_bl.c | 50 ++-- include/linux/pwm_backlight.h |2 + 3 files changed, 50 insertions(+), 4 deletions(-) diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt index 1e4fc72..1ed4f0f 100644 --- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt +++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt @@ -14,6 +14,8 @@ Required properties: Optional properties: - pwm-names: a list of names for the PWM devices specified in the pwms property (see PWM binding[0]) + - enable-gpio: a GPIO that needs to be used to enable the backlight According to Documentation/devicetree/bindings/gpio/gpio.txt this should be called enable-gpios. + - enable-gpio-active-high: polarity of GPIO is active high (default is low) There is OF_GPIO_ACTIVE_LOW, which is automatically parsed from the second cell of a GPIO specifier. It will only work if you request the GPIO using of_get_named_gpio_flags(), though, so it will only work in the non-DT case. I think using a regulator would be more appropriate, since it gives you more flexibility than a plain GPIO. Does anybody see a problem with using a regulator instead? Thierry pgpOelTVTf4Oe.pgp Description: PGP signature
