From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933252AbcFMBFU (ORCPT ); Sun, 12 Jun 2016 21:05:20 -0400 Received: from devils.ext.ti.com ([198.47.26.153]:41664 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932974AbcFMBFR (ORCPT ); Sun, 12 Jun 2016 21:05:17 -0400 Subject: Re: [PATCH v2] backlight: lp855x: Add enable regulator To: Brian Norris References: <1465587597-131467-1-git-send-email-briannorris@chromium.org> CC: Jingoo Han , Lee Jones , Stephen Barber , Doug Anderson , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , , , From: "Kim, Milo" Message-ID: <575E06C3.4020305@ti.com> Date: Mon, 13 Jun 2016 10:05:07 +0900 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <1465587597-131467-1-git-send-email-briannorris@chromium.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Acked-by: Milo Kim 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 > #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); >