From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Thompson Date: Mon, 09 Sep 2019 10:57:29 +0000 Subject: Re: [PATCH 1/2] backlight: lm3630a: add an enable gpio for the HWEN pin Message-Id: <20190909105729.w5552rtop7rhghy2@holly.lan> List-Id: References: <20190908203704.30147-1-andreas@kemnade.info> <20190908203704.30147-2-andreas@kemnade.info> In-Reply-To: <20190908203704.30147-2-andreas@kemnade.info> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andreas Kemnade Cc: lee.jones@linaro.org, jingoohan1@gmail.com, jacek.anaszewski@gmail.com, pavel@ucw.cz, dmurphy@ti.com, robh+dt@kernel.org, mark.rutland@arm.com, b.zolnierkie@samsung.com, dri-devel@lists.freedesktop.org, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org, "H. Nikolaus Schaller" On Sun, Sep 08, 2019 at 10:37:03PM +0200, Andreas Kemnade wrote: > For now just enable it in the probe function to allow i2c > access and disable it on remove. Disabling also means resetting > the register values to default. > > Tested on Kobo Clara HD. > > Signed-off-by: Andreas Kemnade > --- > drivers/video/backlight/lm3630a_bl.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c > index b04b35d007a2..3b45a1733198 100644 > --- a/drivers/video/backlight/lm3630a_bl.c > +++ b/drivers/video/backlight/lm3630a_bl.c > @@ -12,6 +12,8 @@ > #include > #include > #include > +#include > +#include > #include > #include > > @@ -48,6 +50,7 @@ struct lm3630a_chip { > struct lm3630a_platform_data *pdata; > struct backlight_device *bleda; > struct backlight_device *bledb; > + struct gpio_desc *enable_gpio; > struct regmap *regmap; > struct pwm_device *pwmd; > }; > @@ -506,6 +509,14 @@ static int lm3630a_probe(struct i2c_client *client, > return -ENOMEM; > pchip->dev = &client->dev; > > + pchip->enable_gpio = devm_gpiod_get_optional(&client->dev, "enable", > + GPIOD_ASIS); Initializing GPIOD_ASIS doesn't look right to me. If you initialize ASIS then the driver must configure the pin as an output... far easier just to set GPIOD_OUT_HIGH during the get. Note also that the call to this function should also be moved *below* the calls parse the DT. > + if (IS_ERR(pchip->enable_gpio)) { > + rval = PTR_ERR(pchip->enable_gpio); > + return rval; > + } > + > + > pchip->regmap = devm_regmap_init_i2c(client, &lm3630a_regmap); > if (IS_ERR(pchip->regmap)) { > rval = PTR_ERR(pchip->regmap); > @@ -535,6 +546,10 @@ static int lm3630a_probe(struct i2c_client *client, > } > pchip->pdata = pdata; > > + if (pchip->enable_gpio) { > + gpiod_set_value_cansleep(pchip->enable_gpio, 1); Not needed, use GPIOD_OUT_HIGH instead. > + usleep_range(1000, 2000); Not needed, this sleep is already part of lm3630a_chip_init(). > + } > /* chip initialize */ > rval = lm3630a_chip_init(pchip); > if (rval < 0) { > @@ -586,6 +601,9 @@ static int lm3630a_remove(struct i2c_client *client) > if (rval < 0) > dev_err(pchip->dev, "i2c failed to access register\n"); > > + if (pchip->enable_gpio) > + gpiod_set_value_cansleep(pchip->enable_gpio, 0); > + Is this needed? This is a remove path, not a power management path, and we have no idea what the original status of the pin was anyway? > if (pchip->irq) { > free_irq(pchip->irq, pchip); > flush_workqueue(pchip->irqthread); > -- > 2.20.1 >