From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Norris Date: Fri, 10 Jun 2016 19:39:57 +0000 Subject: [PATCH v2] backlight: lp855x: Add enable regulator Message-Id: <1465587597-131467-1-git-send-email-briannorris@chromium.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Milo Kim , Jingoo Han , Lee Jones Cc: Stephen Barber , Doug Anderson , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , Brian Norris , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-fbdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org 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 --- 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 #include #include +#include #include #include #include @@ -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