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From:   Alistair Francis <alistair23@gmail.com>
Date:   Tue, 27 Apr 2021 15:56:40 +1000
Message-ID: <CAKmqyKPOnUOH7idpKa62fSgj2SVSFZLuenGS-LfHJ9uOqPZBpg@mail.gmail.com>
Subject: Re: [PATCH v4 07/10] Input: wacom_i2c - Add support for reset control
To:     Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc:     Alistair Francis <alistair@alistair23.me>,
        linux-input@vger.kernel.org, dl-linux-imx <linux-imx@nxp.com>,
        Sascha Hauer <kernel@pengutronix.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Alistair Francis <alistair@alistair22.me>
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On Tue, Mar 30, 2021 at 6:33 AM Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
>
> Hi Alistair,
>
> On Thu, Mar 25, 2021 at 09:52:27PM -0400, Alistair Francis wrote:
> > From: Alistair Francis <alistair@alistair22.me>
> >
> > Signed-off-by: Alistair Francis <alistair@alistair22.me>
> > ---
> > v4:
> >  - Initial commit
> >
> >  drivers/input/touchscreen/wacom_i2c.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/drivers/input/touchscreen/wacom_i2c.c b/drivers/input/touchscreen/wacom_i2c.c
> > index 84c7ccb737bd..28004b1180c9 100644
> > --- a/drivers/input/touchscreen/wacom_i2c.c
> > +++ b/drivers/input/touchscreen/wacom_i2c.c
> > @@ -55,6 +55,7 @@ struct wacom_features {
> >  struct wacom_i2c {
> >       struct i2c_client *client;
> >       struct input_dev *input;
> > +     struct reset_control *rstc;
> >       struct touchscreen_properties props;
> >       u8 data[WACOM_QUERY_SIZE];
> >       bool prox;
> > @@ -175,6 +176,8 @@ static int wacom_i2c_open(struct input_dev *dev)
> >       struct wacom_i2c *wac_i2c = input_get_drvdata(dev);
> >       struct i2c_client *client = wac_i2c->client;
> >
> > +     reset_control_reset(wac_i2c->rstc);
>
> Why does this device need to be reset on every open compared to doing it
> in probe?
>
> > +
> >       enable_irq(client->irq);
> >
> >       return 0;
> > @@ -193,6 +196,7 @@ static int wacom_i2c_probe(struct i2c_client *client,
> >  {
> >       struct wacom_i2c *wac_i2c;
> >       struct input_dev *input;
> > +     struct reset_control *rstc;
> >       struct wacom_features features = { 0 };
> >       int error;
> >
> > @@ -201,6 +205,12 @@ static int wacom_i2c_probe(struct i2c_client *client,
> >               return -EIO;
> >       }
> >
> > +     rstc = devm_reset_control_get_optional_exclusive(&client->dev, NULL);
> > +     if (IS_ERR(rstc)) {
> > +             dev_err(&client->dev, "Failed to get reset control before init\n");
> > +             return PTR_ERR(rstc);
> > +     }
>
> I think majority users will have this controller reset line connected to
> a GPIO. I briefly looked into reset controller code and I do not see it
> supporting this case. How is this device connected on your board?

That's a good question. I am going to drop this patch as I'm not
convinced it's required.

Alistair

>
> > +
> >       error = wacom_query_device(client, &features);
> >       if (error)
> >               return error;
> > @@ -214,6 +224,7 @@ static int wacom_i2c_probe(struct i2c_client *client,
> >
> >       wac_i2c->client = client;
> >       wac_i2c->input = input;
> > +     wac_i2c->rstc = rstc;
> >
> >       input->name = "Wacom I2C Digitizer";
> >       input->id.bustype = BUS_I2C;
> > --
> > 2.31.0
> >
>
> Thanks.
>
> --
> Dmitry