linux-kernel - Re: [PATCH v2 9/9] media: i2c: tw9910: Remove soc

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Date:   Wed, 3 Jan 2018 16:14:35 -0200
From:   Fabio Estevam <festevam@...il.com>
To:     jacopo mondi <jacopo@...ndi.org>
Cc:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Magnus Damm <magnus.damm@...il.com>, geert@...der.be,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-renesas-soc@...r.kernel.org,
        linux-media <linux-media@...r.kernel.org>,
        linux-sh@...r.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 9/9] media: i2c: tw9910: Remove soc_camera dependencies

On Wed, Jan 3, 2018 at 3:37 PM, jacopo mondi <jacopo@...ndi.org> wrote:

>> Initially the rest GPIO was doing:
>>
>> -       gpio_set_value(GPIO_PTT3, 0);
>> -       mdelay(10);
>> -       gpio_set_value(GPIO_PTT3, 1);
>> -       mdelay(10); /* wait to let chip come out of reset */
>
> And that's what my driver code does :)

No, on 5/9 you converted the original code to:

GPIO_LOOKUP("sh7722_pfc", GPIO_PTT3, "rstb", GPIO_ACTIVE_HIGH)

It should be GPIO_ACTIVE_LOW instead.

> My point is that if I read the manual and I see an active low gpio (0
> is reset state) then the driver code uses it as and active high one (1
> is the reset state), that would be weird to me.

Then on this patch you should do:

gpiod_set_value(priv->rstb_gpio, 1);  ---> This tells the GPIO to go
to its active state (In this case active == logic level 0)
usleep_range(500, 1000);
gpiod_set_value(priv->rstb_gpio, 0); ---> This tells the GPIO to go to
its inactive state (In this case inactive == logic level 1)

You can also look at Documentation/gpio/consumer.txt where the usage
of the gpiod_xxx API is described.

It seems you are confusing it with the legacy gpio_set_value() API
(Documentation/gpio/gpio-legacy.txt)

Hope this helps.