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

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Date:   Wed, 3 Jan 2018 15:27:53 -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

Hi Jacopo,

On Wed, Jan 3, 2018 at 3:13 PM, jacopo mondi <jacopo@...ndi.org> wrote:

> That would be true if I would have declared the GPIO to be ACTIVE_LOW.
> See patch [5/9] in this series and search for "rstb". The GPIO (which
> is shared between two devices) is said to be active high...

Just looked at your patch 5/9 and it seems it only works because you
made two inversions :-)

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 */

So this is an active low reset.

So you should have converted it to:

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

and then in this patch you should do as I said earlier:

gpiod_set_value(priv->rstb_gpio, 1);
usleep_range(500, 1000);
gpiod_set_value(priv->rstb_gpio, 0);