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Date:   Mon, 23 Jul 2018 15:39:26 -0700
From:   Dmitry Torokhov <dmitry.torokhov@gmail.com>
To:     =?iso-8859-1?Q?Myl=E8ne?= Josserand 
        <mylene.josserand@bootlin.com>, robh+dt@kernel.org,
        mark.rutland@arm.com, maxime.ripard@bootlin.com, wens@csie.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        thomas.petazzoni@bootlin.com, linux-input@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/3] Input: edt-ft5x06 - Add support for regulator
Message-ID: <20180723223926.GL100814@dtor-ws>
References: <20180718182719.29663-1-mylene.josserand@bootlin.com>
 <20180718182719.29663-2-mylene.josserand@bootlin.com>
 <20180718224645.ns7nvqxvqc6huxcz@core>
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On Thu, Jul 19, 2018 at 12:46:45AM +0200, Ondřej Jirman wrote:
> Hello Mylène,
> 
> On Wed, Jul 18, 2018 at 08:27:17PM +0200, Mylène Josserand wrote:
> > Add the support of regulator to use it as VCC source.
> > 
> > Signed-off-by: Mylène Josserand <mylene.josserand@bootlin.com>
> > ---
> >  .../bindings/input/touchscreen/edt-ft5x06.txt      |  1 +
> >  drivers/input/touchscreen/edt-ft5x06.c             | 29 ++++++++++++++++++++++
> >  2 files changed, 30 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt
> > index 025cf8c9324a..48e975b9c1aa 100644
> > --- a/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt
> > +++ b/Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt
> > @@ -30,6 +30,7 @@ Required properties:
> >  Optional properties:
> >   - reset-gpios: GPIO specification for the RESET input
> >   - wake-gpios:  GPIO specification for the WAKE input
> > + - vcc-supply:  Regulator that supplies the touchscreen
> >  
> >   - pinctrl-names: should be "default"
> >   - pinctrl-0:   a phandle pointing to the pin settings for the
> > diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
> > index 1e18ca0d1b4e..aa94494b06b5 100644
> > --- a/drivers/input/touchscreen/edt-ft5x06.c
> > +++ b/drivers/input/touchscreen/edt-ft5x06.c
> > @@ -39,6 +39,7 @@
> >  #include <linux/input/mt.h>
> >  #include <linux/input/touchscreen.h>
> >  #include <linux/of_device.h>
> > +#include <linux/regulator/consumer.h>
> >  
> >  #define WORK_REGISTER_THRESHOLD		0x00
> >  #define WORK_REGISTER_REPORT_RATE	0x08
> > @@ -91,6 +92,7 @@ struct edt_ft5x06_ts_data {
> >  	struct touchscreen_properties prop;
> >  	u16 num_x;
> >  	u16 num_y;
> > +	struct regulator *vcc;
> >  
> >  	struct gpio_desc *reset_gpio;
> >  	struct gpio_desc *wake_gpio;
> > @@ -991,6 +993,22 @@ static int edt_ft5x06_ts_probe(struct i2c_client *client,
> >  
> >  	tsdata->max_support_points = chip_data->max_support_points;
> >  
> > +	tsdata->vcc = devm_regulator_get(&client->dev, "vcc");
> > +	if (IS_ERR(tsdata->vcc)) {
> > +		error = PTR_ERR(tsdata->vcc);
> > +		if (error != -EPROBE_DEFER)
> > +			dev_err(&client->dev, "failed to request regulator: %d\n",
> > +				error);
> > +		return error;
> > +	}
> > +
> > +	error = regulator_enable(tsdata->vcc);
> > +	if (error < 0) {
> > +		dev_err(&client->dev, "failed to enable vcc: %d\n",
> > +			error);
> > +		return error;
> > +	}
> > +
> >  	tsdata->reset_gpio = devm_gpiod_get_optional(&client->dev,
> >  						     "reset", GPIOD_OUT_HIGH);
> >  	if (IS_ERR(tsdata->reset_gpio)) {

You need to disable regulator here. We do not have
devm_regulator_enable() (and Mark had some concerns about mixing managed
and unmanaged APIs for regulators so we can't simply introduce it),
so I'd recommend using devm_add_action_or_reset() and iunstall custom
action to turn off regulator.

> > @@ -1120,20 +1138,31 @@ static int edt_ft5x06_ts_remove(struct i2c_client *client)
> >  static int __maybe_unused edt_ft5x06_ts_suspend(struct device *dev)
> >  {
> >  	struct i2c_client *client = to_i2c_client(dev);
> > +	struct edt_ft5x06_ts_data *tsdata = i2c_get_clientdata(client);
> >  
> >  	if (device_may_wakeup(dev))
> >  		enable_irq_wake(client->irq);
> >  
> > +	regulator_disable(tsdata->vcc);
> > +
> 
> How will the touchscreen wakeup the system with interrupt if you power it off
> on suspend? Perhaps guard this with device_may_wakeup() too? 

Exactly, it should be in an "else" branch.

Thanks.

-- 
Dmitry