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authorBrian Norris <briannorris@chromium.org>2016-06-10 12:39:57 -0700
committerLee Jones <lee.jones@linaro.org>2016-06-29 10:06:21 +0100
commit602553073892c18f723f8aa090153a23b1312a16 (patch)
treef6b898ed187ef7cf1134e46bf914f49732a783cc /drivers/video
parentaf8c34ce6ae32addda3788d54a7e340cad22516b (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')
-rw-r--r--drivers/video/backlight/lp855x_bl.c29
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);