diff options
| author | Brian Norris <briannorris@chromium.org> | 2016-06-10 12:39:57 -0700 |
|---|---|---|
| committer | Lee Jones <lee.jones@linaro.org> | 2016-06-29 10:06:21 +0100 |
| commit | 602553073892c18f723f8aa090153a23b1312a16 (patch) | |
| tree | f6b898ed187ef7cf1134e46bf914f49732a783cc /drivers/video/backlight | |
| parent | af8c34ce6ae32addda3788d54a7e340cad22516b (diff) | |
backlight: lp855x: Add enable regulator
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: Rob Herring <robh@kernel.org>
Acked-by: Milo Kim <milo.kim@ti.com>
Reviewed-by: Stephen Barber <smbarber@chromium.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Diffstat (limited to 'drivers/video/backlight')
| -rw-r--r-- | drivers/video/backlight/lp855x_bl.c | 29 |
1 files changed, 29 insertions, 0 deletions
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); |