From:   Luca Weiss <luca@z3ntu.xyz>
To:     Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Cc:     ~postmarketos/upstreaming@lists.sr.ht, phone-devel@vger.kernel.org,
        Shunqian Zheng <zhengsq@rock-chips.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Jacopo Mondi <jacopo.mondi@ideasonboard.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] media: i2c: ov2685: Make reset gpio optional
Date:   Sun, 29 Jan 2023 12:49:03 +0100
Message-ID: <2543677.Lt9SDvczpP@g550jk>
In-Reply-To: <20230129112249.lf2vb7pthrv4nien@uno.localdomain>
References: <20230129-ov2685-improvements-v1-0-f281bd49399c@z3ntu.xyz>
 <20230129-ov2685-improvements-v1-1-f281bd49399c@z3ntu.xyz>
 <20230129112249.lf2vb7pthrv4nien@uno.localdomain>
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset="iso-8859-1"
Precedence: bulk

On Sonntag, 29. J=E4nner 2023 12:22:49 CET Jacopo Mondi wrote:
> Hi Luca
>=20
> On Sun, Jan 29, 2023 at 10:42:35AM +0100, Luca Weiss wrote:
> > In some setups XSHUTDOWN is connected to DOVDD when it's unused,
> > therefore treat the reset gpio as optional.
>=20
> I don't have a datasheet for this sensor, but OV sensors usually have
> to gpio lines to control powerdown and reset. Datasheets usually
> suggest to hook one of the 2 to DOVDD and control the other from the
> SoC. How is the sensor hooked up in your design ? No gpio lines is
> controlled by the SoC ?

It looks like this sensor only has XSHUTDOWN pin and no extra reset pin.

In my setup there's the normal I2C & CSI & mclk hookups, but the supply lin=
es=20
and shutdown line are all just connected to regulator-fixed, so gpio-
controlled on/off regulators.

>=20
> Another question is if we need to software-reset the sensor if no gpio
> line is hooked up to XSHUTDOWN.

The datasheet mentions it resets itself during power up (so when the suppli=
es=20
are turned on), so I don't think we need to add anything.

Regards
Luca

>=20
> > Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
> > ---
> >=20
> >  drivers/media/i2c/ov2685.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >=20
> > diff --git a/drivers/media/i2c/ov2685.c b/drivers/media/i2c/ov2685.c
> > index a3b524f15d89..a422f4c8a2eb 100644
> > --- a/drivers/media/i2c/ov2685.c
> > +++ b/drivers/media/i2c/ov2685.c
> > @@ -734,7 +734,7 @@ static int ov2685_probe(struct i2c_client *client,
> >=20
> >  	if (clk_get_rate(ov2685->xvclk) !=3D OV2685_XVCLK_FREQ)
> >  =09
> >  		dev_warn(dev, "xvclk mismatched, modes are based on=20
24MHz\n");
> >=20
> > -	ov2685->reset_gpio =3D devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> > +	ov2685->reset_gpio =3D devm_gpiod_get_optional(dev, "reset",
> > GPIOD_OUT_LOW);>=20
> >  	if (IS_ERR(ov2685->reset_gpio)) {
> >  =09
> >  		dev_err(dev, "Failed to get reset-gpios\n");
> >  		return -EINVAL;
> >=20
> > --
> > 2.39.1