[PATCH v2] backlight: lp855x: Add enable regulator

[PATCH v2] backlight: lp855x: Add enable regulator

[Brian Norris]

The LP8556 datasheet describes an EN/VDDIO input, which serves "both as
a chip enable and as a power supply reference for PWM, SDA, and SCL
inputs." The LP8556 that I'm testing doesn't respond properly if I try
to talk I2C to it too quickly after enabling VDDIO, and the LP8555
datasheet mentions a t_RESPONSE delay of up to 1 millisecond.

Support this EN/VDDIO by adding a regulator property to the binding;
enabling this regulator at probe time; and sleeping for 1 to 2ms, if the
EN/VDDIO regulator was provided.

Signed-off-by: Brian Norris <briannorris@chromium.org>
---
v2: s/TS8555/LP8555/ in comment (typo)

 .../devicetree/bindings/leds/backlight/lp855x.txt  |  2 ++
 drivers/video/backlight/lp855x_bl.c                | 29 ++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
index 0a3ecbc3a1b9..88f56641fc28 100644
--- a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
+++ b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
@@ -13,6 +13,7 @@ Optional properties:
   - rom-addr: Register address of ROM area to be updated (u8)
   - rom-val: Register value to be updated (u8)
   - power-supply: Regulator which controls the 3V rail
+  - enable-supply: Regulator which controls the EN/VDDIO input
 
 Example:
 
@@ -57,6 +58,7 @@ Example:
 	backlight@2c {
 		compatible = "ti,lp8557";
 		reg = <0x2c>;
+		enable-supply = <&backlight_vddio>;
 		power-supply = <&backlight_vdd>;
 
 		dev-ctrl = /bits/ 8 <0x41>;
diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
index e5b14f52628f..939f057836e1 100644
--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c
@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/backlight.h>
+#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/of.h>
 #include <linux/platform_data/lp855x.h>
@@ -74,6 +75,7 @@ struct lp855x {
 	struct lp855x_platform_data *pdata;
 	struct pwm_device *pwm;
 	struct regulator *supply;	/* regulator for VDD input */
+	struct regulator *enable;	/* regulator for EN/VDDIO input */
 };
 
 static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
@@ -433,6 +435,19 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 		lp->supply = NULL;
 	}
 
+	lp->enable = devm_regulator_get_optional(lp->dev, "enable");
+	if (IS_ERR(lp->enable)) {
+		ret = PTR_ERR(lp->enable);
+		if (ret == -ENODEV) {
+			lp->enable = NULL;
+		} else {
+			if (ret != -EPROBE_DEFER)
+				dev_err(lp->dev, "error getting enable regulator: %d\n",
+					ret);
+			return ret;
+		}
+	}
+
 	if (lp->supply) {
 		ret = regulator_enable(lp->supply);
 		if (ret < 0) {
@@ -441,6 +456,20 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
 		}
 	}
 
+	if (lp->enable) {
+		ret = regulator_enable(lp->enable);
+		if (ret < 0) {
+			dev_err(lp->dev, "failed to enable vddio: %d\n", ret);
+			return ret;
+		}
+
+		/*
+		 * LP8555 datasheet says t_RESPONSE (time between VDDIO and
+		 * I2C) is 1ms.
+		 */
+		usleep_range(1000, 2000);
+	}
+
 	i2c_set_clientdata(cl, lp);
 
 	ret = lp855x_configure(lp);
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH v2] backlight: lp855x: Add enable regulator

[Stephen Barber]

On Fri, Jun 10, 2016 at 12:39 PM, Brian Norris <briannorris@chromium.org> wrote:
>
> The LP8556 datasheet describes an EN/VDDIO input, which serves "both as
> a chip enable and as a power supply reference for PWM, SDA, and SCL
> inputs." The LP8556 that I'm testing doesn't respond properly if I try
> to talk I2C to it too quickly after enabling VDDIO, and the LP8555
> datasheet mentions a t_RESPONSE delay of up to 1 millisecond.
>
> Support this EN/VDDIO by adding a regulator property to the binding;
> enabling this regulator at probe time; and sleeping for 1 to 2ms, if the
> EN/VDDIO regulator was provided.
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> v2: s/TS8555/LP8555/ in comment (typo)
>
>  .../devicetree/bindings/leds/backlight/lp855x.txt  |  2 ++
>  drivers/video/backlight/lp855x_bl.c                | 29 ++++++++++++++++++++++
>  2 files changed, 31 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> index 0a3ecbc3a1b9..88f56641fc28 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> +++ b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> @@ -13,6 +13,7 @@ Optional properties:
>    - rom-addr: Register address of ROM area to be updated (u8)
>    - rom-val: Register value to be updated (u8)
>    - power-supply: Regulator which controls the 3V rail
> +  - enable-supply: Regulator which controls the EN/VDDIO input
>
>  Example:
>
> @@ -57,6 +58,7 @@ Example:
>         backlight@2c {
>                 compatible = "ti,lp8557";
>                 reg = <0x2c>;
> +               enable-supply = <&backlight_vddio>;
>                 power-supply = <&backlight_vdd>;
>
>                 dev-ctrl = /bits/ 8 <0x41>;
> diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
> index e5b14f52628f..939f057836e1 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -13,6 +13,7 @@
>  #include <linux/slab.h>
>  #include <linux/i2c.h>
>  #include <linux/backlight.h>
> +#include <linux/delay.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
>  #include <linux/platform_data/lp855x.h>
> @@ -74,6 +75,7 @@ struct lp855x {
>         struct lp855x_platform_data *pdata;
>         struct pwm_device *pwm;
>         struct regulator *supply;       /* regulator for VDD input */
> +       struct regulator *enable;       /* regulator for EN/VDDIO input */
>  };
>
>  static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
> @@ -433,6 +435,19 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>                 lp->supply = NULL;
>         }
>
> +       lp->enable = devm_regulator_get_optional(lp->dev, "enable");
> +       if (IS_ERR(lp->enable)) {
> +               ret = PTR_ERR(lp->enable);
> +               if (ret == -ENODEV) {
> +                       lp->enable = NULL;
> +               } else {
> +                       if (ret != -EPROBE_DEFER)
> +                               dev_err(lp->dev, "error getting enable regulator: %d\n",
> +                                       ret);
> +                       return ret;
> +               }
> +       }
> +
>         if (lp->supply) {
>                 ret = regulator_enable(lp->supply);
>                 if (ret < 0) {
> @@ -441,6 +456,20 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>                 }
>         }
>
> +       if (lp->enable) {
> +               ret = regulator_enable(lp->enable);
> +               if (ret < 0) {
> +                       dev_err(lp->dev, "failed to enable vddio: %d\n", ret);
> +                       return ret;
> +               }
> +
> +               /*
> +                * LP8555 datasheet says t_RESPONSE (time between VDDIO and
> +                * I2C) is 1ms.
> +                */
> +               usleep_range(1000, 2000);
> +       }
> +
>         i2c_set_clientdata(cl, lp);
>
>         ret = lp855x_configure(lp);
> --
> 2.8.0.rc3.226.g39d4020
>

Reviewed-by: Stephen Barber <smbarber@chromium.org>

Steve

Re: [PATCH v2] backlight: lp855x: Add enable regulator

[Kim, Milo]

On 6/11/2016 4:39 AM, Brian Norris wrote:
> The LP8556 datasheet describes an EN/VDDIO input, which serves "both as
> a chip enable and as a power supply reference for PWM, SDA, and SCL
> inputs." The LP8556 that I'm testing doesn't respond properly if I try
> to talk I2C to it too quickly after enabling VDDIO, and the LP8555
> datasheet mentions a t_RESPONSE delay of up to 1 millisecond.
>
> Support this EN/VDDIO by adding a regulator property to the binding;
> enabling this regulator at probe time; and sleeping for 1 to 2ms, if the
> EN/VDDIO regulator was provided.
>
> Signed-off-by: Brian Norris <briannorris@chromium.org>

Acked-by: Milo Kim <milo.kim@ti.com>

Thanks!

> ---
> v2: s/TS8555/LP8555/ in comment (typo)
>
>   .../devicetree/bindings/leds/backlight/lp855x.txt  |  2 ++
>   drivers/video/backlight/lp855x_bl.c                | 29 ++++++++++++++++++++++
>   2 files changed, 31 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> index 0a3ecbc3a1b9..88f56641fc28 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> +++ b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> @@ -13,6 +13,7 @@ Optional properties:
>     - rom-addr: Register address of ROM area to be updated (u8)
>     - rom-val: Register value to be updated (u8)
>     - power-supply: Regulator which controls the 3V rail
> +  - enable-supply: Regulator which controls the EN/VDDIO input
>
>   Example:
>
> @@ -57,6 +58,7 @@ Example:
>   	backlight@2c {
>   		compatible = "ti,lp8557";
>   		reg = <0x2c>;
> +		enable-supply = <&backlight_vddio>;
>   		power-supply = <&backlight_vdd>;
>
>   		dev-ctrl = /bits/ 8 <0x41>;
> diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
> index e5b14f52628f..939f057836e1 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -13,6 +13,7 @@
>   #include <linux/slab.h>
>   #include <linux/i2c.h>
>   #include <linux/backlight.h>
> +#include <linux/delay.h>
>   #include <linux/err.h>
>   #include <linux/of.h>
>   #include <linux/platform_data/lp855x.h>
> @@ -74,6 +75,7 @@ struct lp855x {
>   	struct lp855x_platform_data *pdata;
>   	struct pwm_device *pwm;
>   	struct regulator *supply;	/* regulator for VDD input */
> +	struct regulator *enable;	/* regulator for EN/VDDIO input */
>   };
>
>   static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
> @@ -433,6 +435,19 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>   		lp->supply = NULL;
>   	}
>
> +	lp->enable = devm_regulator_get_optional(lp->dev, "enable");
> +	if (IS_ERR(lp->enable)) {
> +		ret = PTR_ERR(lp->enable);
> +		if (ret == -ENODEV) {
> +			lp->enable = NULL;
> +		} else {
> +			if (ret != -EPROBE_DEFER)
> +				dev_err(lp->dev, "error getting enable regulator: %d\n",
> +					ret);
> +			return ret;
> +		}
> +	}
> +
>   	if (lp->supply) {
>   		ret = regulator_enable(lp->supply);
>   		if (ret < 0) {
> @@ -441,6 +456,20 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>   		}
>   	}
>
> +	if (lp->enable) {
> +		ret = regulator_enable(lp->enable);
> +		if (ret < 0) {
> +			dev_err(lp->dev, "failed to enable vddio: %d\n", ret);
> +			return ret;
> +		}
> +
> +		/*
> +		 * LP8555 datasheet says t_RESPONSE (time between VDDIO and
> +		 * I2C) is 1ms.
> +		 */
> +		usleep_range(1000, 2000);
> +	}
> +
>   	i2c_set_clientdata(cl, lp);
>
>   	ret = lp855x_configure(lp);
>

Re: [PATCH v2] backlight: lp855x: Add enable regulator

[Rob Herring]

On Fri, Jun 10, 2016 at 12:39:57PM -0700, Brian Norris wrote:
> The LP8556 datasheet describes an EN/VDDIO input, which serves "both as
> a chip enable and as a power supply reference for PWM, SDA, and SCL
> inputs." The LP8556 that I'm testing doesn't respond properly if I try
> to talk I2C to it too quickly after enabling VDDIO, and the LP8555
> datasheet mentions a t_RESPONSE delay of up to 1 millisecond.
> 
> Support this EN/VDDIO by adding a regulator property to the binding;
> enabling this regulator at probe time; and sleeping for 1 to 2ms, if the
> EN/VDDIO regulator was provided.
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> v2: s/TS8555/LP8555/ in comment (typo)
> 
>  .../devicetree/bindings/leds/backlight/lp855x.txt  |  2 ++

I would have picked 'vddio' as the name, but it's fine.

Acked-by: Rob Herring <robh@kernel.org>

>  drivers/video/backlight/lp855x_bl.c                | 29 ++++++++++++++++++++++
>  2 files changed, 31 insertions(+)

Re: [PATCH v2] backlight: lp855x: Add enable regulator

[Lee Jones]

On Fri, 10 Jun 2016, Brian Norris wrote:

> The LP8556 datasheet describes an EN/VDDIO input, which serves "both as
> a chip enable and as a power supply reference for PWM, SDA, and SCL
> inputs." The LP8556 that I'm testing doesn't respond properly if I try
> to talk I2C to it too quickly after enabling VDDIO, and the LP8555
> datasheet mentions a t_RESPONSE delay of up to 1 millisecond.
> 
> Support this EN/VDDIO by adding a regulator property to the binding;
> enabling this regulator at probe time; and sleeping for 1 to 2ms, if the
> EN/VDDIO regulator was provided.
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> ---
> v2: s/TS8555/LP8555/ in comment (typo)
> 
>  .../devicetree/bindings/leds/backlight/lp855x.txt  |  2 ++
>  drivers/video/backlight/lp855x_bl.c                | 29 ++++++++++++++++++++++
>  2 files changed, 31 insertions(+)

Collected Acks and applied, thanks.

> diff --git a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> index 0a3ecbc3a1b9..88f56641fc28 100644
> --- a/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> +++ b/Documentation/devicetree/bindings/leds/backlight/lp855x.txt
> @@ -13,6 +13,7 @@ Optional properties:
>    - rom-addr: Register address of ROM area to be updated (u8)
>    - rom-val: Register value to be updated (u8)
>    - power-supply: Regulator which controls the 3V rail
> +  - enable-supply: Regulator which controls the EN/VDDIO input
>  
>  Example:
>  
> @@ -57,6 +58,7 @@ Example:
>  	backlight@2c {
>  		compatible = "ti,lp8557";
>  		reg = <0x2c>;
> +		enable-supply = <&backlight_vddio>;
>  		power-supply = <&backlight_vdd>;
>  
>  		dev-ctrl = /bits/ 8 <0x41>;
> diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c
> index e5b14f52628f..939f057836e1 100644
> --- a/drivers/video/backlight/lp855x_bl.c
> +++ b/drivers/video/backlight/lp855x_bl.c
> @@ -13,6 +13,7 @@
>  #include <linux/slab.h>
>  #include <linux/i2c.h>
>  #include <linux/backlight.h>
> +#include <linux/delay.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
>  #include <linux/platform_data/lp855x.h>
> @@ -74,6 +75,7 @@ struct lp855x {
>  	struct lp855x_platform_data *pdata;
>  	struct pwm_device *pwm;
>  	struct regulator *supply;	/* regulator for VDD input */
> +	struct regulator *enable;	/* regulator for EN/VDDIO input */
>  };
>  
>  static int lp855x_write_byte(struct lp855x *lp, u8 reg, u8 data)
> @@ -433,6 +435,19 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>  		lp->supply = NULL;
>  	}
>  
> +	lp->enable = devm_regulator_get_optional(lp->dev, "enable");
> +	if (IS_ERR(lp->enable)) {
> +		ret = PTR_ERR(lp->enable);
> +		if (ret == -ENODEV) {
> +			lp->enable = NULL;
> +		} else {
> +			if (ret != -EPROBE_DEFER)
> +				dev_err(lp->dev, "error getting enable regulator: %d\n",
> +					ret);
> +			return ret;
> +		}
> +	}
> +
>  	if (lp->supply) {
>  		ret = regulator_enable(lp->supply);
>  		if (ret < 0) {
> @@ -441,6 +456,20 @@ static int lp855x_probe(struct i2c_client *cl, const struct i2c_device_id *id)
>  		}
>  	}
>  
> +	if (lp->enable) {
> +		ret = regulator_enable(lp->enable);
> +		if (ret < 0) {
> +			dev_err(lp->dev, "failed to enable vddio: %d\n", ret);
> +			return ret;
> +		}
> +
> +		/*
> +		 * LP8555 datasheet says t_RESPONSE (time between VDDIO and
> +		 * I2C) is 1ms.
> +		 */
> +		usleep_range(1000, 2000);
> +	}
> +
>  	i2c_set_clientdata(cl, lp);
>  
>  	ret = lp855x_configure(lp);

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
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