From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Date: Wed, 15 Jun 2016 08:34:45 +0000 Subject: Re: [PATCH v2] backlight: lp855x: Add enable regulator Message-Id: <20160615083445.GA1579@dell> List-Id: References: <1465587597-131467-1-git-send-email-briannorris@chromium.org> In-Reply-To: <1465587597-131467-1-git-send-email-briannorris@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable To: Brian Norris Cc: Milo Kim , Jingoo Han , Stephen Barber , Doug Anderson , Jean-Christophe Plagniol-Villard , Tomi Valkeinen , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org On Fri, 10 Jun 2016, 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. >=20 > 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. >=20 > Signed-off-by: Brian Norris > --- > v2: s/TS8555/LP8555/ in comment (typo) >=20 > .../devicetree/bindings/leds/backlight/lp855x.txt | 2 ++ > drivers/video/backlight/lp855x_bl.c | 29 ++++++++++++++++= ++++++ > 2 files changed, 31 insertions(+) Collected Acks and applied, thanks. > 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 > =20 > Example: > =20 > @@ -57,6 +58,7 @@ Example: > backlight@2c { > compatible =3D "ti,lp8557"; > reg =3D <0x2c>; > + enable-supply =3D <&backlight_vddio>; > power-supply =3D <&backlight_vdd>; > =20 > dev-ctrl =3D /bits/ 8 <0x41>; > diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backligh= t/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 */ > }; > =20 > 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 =3D NULL; > } > =20 > + lp->enable =3D devm_regulator_get_optional(lp->dev, "enable"); > + if (IS_ERR(lp->enable)) { > + ret =3D PTR_ERR(lp->enable); > + if (ret =3D -ENODEV) { > + lp->enable =3D NULL; > + } else { > + if (ret !=3D -EPROBE_DEFER) > + dev_err(lp->dev, "error getting enable regulator: %d\n", > + ret); > + return ret; > + } > + } > + > if (lp->supply) { > ret =3D 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) > } > } > =20 > + if (lp->enable) { > + ret =3D 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); > =20 > ret =3D lp855x_configure(lp); --=20 Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org =E2=94=82 Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog