Re: [PATCH 1/1 v5] pwm_bl: Add support for backlight enable regulator
From: Alex Courbot
Date: Fri Mar 08 2013 - 01:18:26 EST
On 03/08/2013 06:16 AM, Andrew Chew wrote:
The backlight enable regulator is specified in the device tree node for
backlight.
Signed-off-by: Andrew Chew <achew@xxxxxxxxxx>
---
Renamed en_supply to enable_supply to match the corresponding device tree
property.
Removed unnecessary check for pb->enable_supply validity. This supply
is mandatory, and probe will fail if it is not provided.
Renamed the tracking bool from en_supply_enabled to enabled so that it's
more generic. Encapsulated pwm_enable() and pwm_disable() calls into the
enabled check so that we never unnecessarily turn on or off the pwm if
it's already been turned on or off.
.../bindings/video/backlight/pwm-backlight.txt | 14 +++++
drivers/video/backlight/pwm_bl.c | 56 ++++++++++++++++----
2 files changed, 60 insertions(+), 10 deletions(-)
diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
index 1e4fc72..7e2e089 100644
--- a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
+++ b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
@@ -10,6 +10,11 @@ Required properties:
last value in the array represents a 100% duty cycle (brightest).
- default-brightness-level: the default brightness level (index into the
array defined by the "brightness-levels" property)
+ - enable-supply: A phandle to the regulator device tree node. This
+ regulator will be turned on and off as the pwm is enabled and disabled.
+ Many backlights are enabled via a GPIO. In this case, we instantiate
+ a fixed regulator and give that to enable-supply. If a regulator
+ is not needed, then provide a dummy fixed regulator.
Optional properties:
- pwm-names: a list of names for the PWM devices specified in the
@@ -19,10 +24,19 @@ Optional properties:
Example:
+ bl_en: fixed-regulator {
+ compatible = "regulator-fixed";
+ regulator-name = "bl-en-supply";
+ regulator-boot-on;
+ gpio = <&some_gpio>;
+ enable-active-high;
+ };
+
backlight {
compatible = "pwm-backlight";
pwms = <&pwm 0 5000000>;
brightness-levels = <0 4 8 16 32 64 128 255>;
default-brightness-level = <6>;
+ enable-supply = <&bl_en>;
};
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 069983c..c517d4a 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/regulator/consumer.h>
struct pwm_bl_data {
struct pwm_device *pwm;
struct device *dev;
+ bool enabled;
+ struct regulator *enable_supply;
unsigned int period;
unsigned int lth_brightness;
unsigned int *levels;
@@ -35,6 +38,38 @@ struct pwm_bl_data {
void (*exit)(struct device *);
};
+static void pwm_backlight_enable(struct backlight_device *bl)
+{
+ struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+
+ /* Bail if we are already enabled. */
+ if (pb->enabled)
+ return;
+
+ pwm_enable(pb->pwm);
+
+ if (regulator_enable(pb->enable_supply) != 0)
+ dev_warn(&bl->dev, "Failed to enable regulator");
+
+ pb->enabled = true;
+}
+
+static void pwm_backlight_disable(struct backlight_device *bl)
+{
+ struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+
+ /* Bail if we are already disabled. */
+ if (!pb->enabled)
+ return;
+
+ if (regulator_disable(pb->enable_supply) != 0)
+ dev_warn(&bl->dev, "Failed to disable regulator");
+
+ pwm_disable(pb->pwm);
+
+ pb->enabled = false;
+}
+
static int pwm_backlight_update_status(struct backlight_device *bl)
{
struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
@@ -52,7 +87,7 @@ 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(bl);
} else {
int duty_cycle;
@@ -66,7 +101,7 @@ static int pwm_backlight_update_status(struct backlight_device *bl)
duty_cycle = pb->lth_brightness +
(duty_cycle * (pb->period - pb->lth_brightness) / max);
pwm_config(pb->pwm, duty_cycle, pb->period);
- pwm_enable(pb->pwm);
+ pwm_backlight_enable(bl);
}
if (pb->notify_after)
@@ -145,12 +180,6 @@ static int pwm_backlight_parse_dt(struct device *dev,
data->max_brightness--;
}
- /*
- * TODO: Most users of this driver use a number of GPIOs to control
- * backlight power. Support for specifying these needs to be
- * added.
- */
-
return 0;
}
@@ -213,6 +242,13 @@ static int pwm_backlight_probe(struct platform_device *pdev)
pb->exit = data->exit;
pb->dev = &pdev->dev;
+ pb->enable_supply = devm_regulator_get(&pdev->dev, "enable");
+ if (IS_ERR(pb->enable_supply)) {
+ ret = PTR_ERR(pb->enable_supply);
+ pb->enable_supply = NULL;
I don't think you need to set enable_supply to NULL since probe will
fail anyway.
+ goto err_alloc;
+ }
+
pb->pwm = devm_pwm_get(&pdev->dev, NULL);
if (IS_ERR(pb->pwm)) {
dev_err(&pdev->dev, "unable to request PWM, trying legacy API\n");
@@ -268,7 +304,7 @@ static int pwm_backlight_remove(struct platform_device *pdev)
backlight_device_unregister(bl);
pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ pwm_backlight_disable(bl);
if (pb->exit)
pb->exit(&pdev->dev);
return 0;
@@ -283,7 +319,7 @@ static int pwm_backlight_suspend(struct device *dev)
if (pb->notify)
pb->notify(pb->dev, 0);
pwm_config(pb->pwm, 0, pb->period);
- pwm_disable(pb->pwm);
+ pwm_backlight_disable(bl);
if (pb->notify_after)
pb->notify_after(pb->dev, 0);
return 0;
Thierry might have other remarks, but this looks good globally to me, so
Reviewed-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
Alex.
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