linux-kernel - Re: [PATCH 1/4] media: i2c: ov2685: Make reset gpio optional

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Message-ID: <20230129130548.bsqcnjh2lfu4bn2y@uno.localdomain>
Date:   Sun, 29 Jan 2023 14:05:48 +0100
From:   Jacopo Mondi <jacopo.mondi@...asonboard.com>
To:     Luca Weiss <luca@...tu.xyz>
Cc:     Jacopo Mondi <jacopo.mondi@...asonboard.com>,
        ~postmarketos/upstreaming@...ts.sr.ht, phone-devel@...r.kernel.org,
        Shunqian Zheng <zhengsq@...k-chips.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] media: i2c: ov2685: Make reset gpio optional

Hi Luca

On Sun, Jan 29, 2023 at 12:49:03PM +0100, Luca Weiss wrote:
> On Sonntag, 29. Jänner 2023 12:22:49 CET Jacopo Mondi wrote:
> > Hi Luca
> >
> > 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.
> >
> > 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.
>

Ack, I see the same for OV2680 (for which I have a datasheet)

> In my setup there's the normal I2C & CSI & mclk hookups, but the supply lines
> and shutdown line are all just connected to regulator-fixed, so gpio-
> controlled on/off regulators.
>
> >
> > 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 supplies
> are turned on), so I don't think we need to add anything.
>

Thanks for the clarification!

Reviewed-by: Jacopo Mondi <jacopo.mondi@...asonboard.com>

Thanks
   j


> Regards
> Luca
>
> >
> > > Signed-off-by: Luca Weiss <luca@...tu.xyz>
> > > ---
> > >
> > >  drivers/media/i2c/ov2685.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > 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,
> > >
> > >  	if (clk_get_rate(ov2685->xvclk) != OV2685_XVCLK_FREQ)
> > >
> > >  		dev_warn(dev, "xvclk mismatched, modes are based on
> 24MHz\n");
> > >
> > > -	ov2685->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> > > +	ov2685->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> > > GPIOD_OUT_LOW);>
> > >  	if (IS_ERR(ov2685->reset_gpio)) {
> > >
> > >  		dev_err(dev, "Failed to get reset-gpios\n");
> > >  		return -EINVAL;
> > >
> > > --
> > > 2.39.1
>
>
>
>