Re: [PATCH 2/2] backlight/lp855x: Add supply regulator to lp855x

On Wed, Nov 26, 2014 at 5:32 PM, Kim, Milo [off-list ref] wrote:

(Looping backlight class subsystem maintainers)

Hi Sean,

Please see my comments below. Thanks!

On 11/27/2014 4:11 AM, Sean Paul wrote:

quoted

This patch adds a supply regulator to the lp855x platform data to
facilitate
powering on/off the 3V rail attached to the controller.

Cc: Stéphane Marchesin <redacted>
Cc: Aaron Durbin <redacted>
Signed-off-by: Sean Paul <redacted>
---
  .../devicetree/bindings/video/backlight/lp855x.txt      |  2 ++
  drivers/video/backlight/lp855x_bl.c                     | 17
+++++++++++++++++
  include/linux/platform_data/lp855x.h                    |  2 ++
  3 files changed, 21 insertions(+)

diff --git a/Documentation/devicetree/bindings/video/backlight/lp855x.txt

b/Documentation/devicetree/bindings/video/backlight/lp855x.txt
index 96e83a5..0a3ecbc 100644

--- a/Documentation/devicetree/bindings/video/backlight/lp855x.txt
+++ b/Documentation/devicetree/bindings/video/backlight/lp855x.txt

@@ -12,6 +12,7 @@ Optional properties:
    - pwm-period: PWM period value. Set only PWM input mode used (u32)
    - 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

  Example:

@@ -56,6 +57,7 @@ Example:
        backlight@2c {
                compatible = "ti,lp8557";
                reg = <0x2c>;
+               power-supply = <&backlight_vdd>;

                dev-ctrl = /bits/ 8 <0x41>;
                init-brt = /bits/ 8 <0x0a>;

diff --git a/drivers/video/backlight/lp855x_bl.c

b/drivers/video/backlight/lp855x_bl.c
index 257b3ba..8021009 100644

--- a/drivers/video/backlight/lp855x_bl.c
+++ b/drivers/video/backlight/lp855x_bl.c

@@ -17,6 +17,7 @@
  #include <linux/of.h>
  #include <linux/platform_data/lp855x.h>
  #include <linux/pwm.h>
+#include <linux/regulator/consumer.h>

  /* LP8550/1/2/3/6 Registers */
  #define LP855X_BRIGHTNESS_CTRL                0x00

@@ -383,6 +384,13 @@ static int lp855x_parse_dt(struct lp855x *lp)
                pdata->rom_data = &rom[0];
        }

+       pdata->supply = devm_regulator_get(dev, "power");
+       if (IS_ERR(pdata->supply)) {
+               if (PTR_ERR(pdata->supply) = -EPROBE_DEFER)
+                       return -EPROBE_DEFER;
+               pdata->supply = NULL;

This optional data, 'supply' is set to NULL.
Please refer to my comments below.

quoted

+       }
+
        lp->pdata = pdata;

        return 0;

@@ -423,6 +431,14 @@ static int lp855x_probe(struct i2c_client *cl, const

struct i2c_device_id *id)
        else
                lp->mode = REGISTER_BASED;

+       if (lp->pdata->supply) {
+               ret = regulator_enable(lp->pdata->supply);
+               if (ret < 0) {
+                       dev_err(&cl->dev, "failed to enable supply: %d\n",
ret);
+                       return ret;
+               }
+       }
+
        i2c_set_clientdata(cl, lp);

        ret = lp855x_configure(lp);

@@ -454,6 +470,7 @@ static int lp855x_remove(struct i2c_client *cl)

        lp->bl->props.brightness = 0;
        backlight_update_status(lp->bl);
+       regulator_disable(lp->pdata->supply);

The 'lp->pdata->supply' is optional, what happens if it is NULL?
This will cause the kernel OOPS inside regulator_disable() API.

bleh. Thanks for catching this, I'll re-spin and send a new version next week.

Sean

int regulator_disable(struct regulator *regulator)
{
        struct regulator_dev *rdev = regulator->rdev;
...
}

quoted

        sysfs_remove_group(&lp->dev->kobj, &lp855x_attr_group);

        return 0;

diff --git a/include/linux/platform_data/lp855x.h

b/include/linux/platform_data/lp855x.h
index 1b2ba24..9c7fd1e 100644

--- a/include/linux/platform_data/lp855x.h
+++ b/include/linux/platform_data/lp855x.h

@@ -136,6 +136,7 @@ struct lp855x_rom_data {
                Only valid when mode is PWM_BASED.
   * @size_program : total size of lp855x_rom_data
   * @rom_data : list of new eeprom/eprom registers
+ * @supply : regulator that supplies 3V input
   */
  struct lp855x_platform_data {
        const char *name;

@@ -144,6 +145,7 @@ struct lp855x_platform_data {
        unsigned int period_ns;
        int size_program;
        struct lp855x_rom_data *rom_data;
+       struct regulator *supply;
  };

  #endif

Best regards,
Milo