linux-kernel - Re: [EXT] Re: [PATCH 2/2] drm/panel: Add support for Raydium RM67191 panel driver

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Date:   Fri, 14 Jun 2019 13:50:12 +0000
From:   Robert Chiras <robert.chiras@....com>
To:     "festevam@...il.com" <festevam@...il.com>
CC:     dl-linux-imx <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "sam@...nborg.org" <sam@...nborg.org>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "thierry.reding@...il.com" <thierry.reding@...il.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "airlied@...ux.ie" <airlied@...ux.ie>
Subject: Re: [EXT] Re: [PATCH 2/2] drm/panel: Add support for Raydium RM67191
 panel driver

On Vi, 2019-06-14 at 10:39 -0300, Fabio Estevam wrote:
> Caution: EXT Email
> 
> On Fri, Jun 14, 2019 at 10:29 AM Robert Chiras <robert.chiras@....com
> > wrote:
> 
> > 
> > The GPIO is active high, and the above sequence was received from
> > the
> > panel vendor in the following form:
> >         SET_RESET_PIN(1);
> >         MDELAY(10);
> >         SET_RESET_PIN(0);
> >         MDELAY(5);
> >         SET_RESET_PIN(1);
> >         MDELAY(20);
> > I got rid of the first transition to high since seemed redundant.
> > Also, according to the manual reference, the RSTB pin needs to be
> > active high while operating the display.
> That's exactly my point :-)
> 
> In normal operation the GPIO reset needs to be high.
> 
> During reset the GPIO reset needs to be low., which means that the
> GPIO reset is "active low".
> 
> So you should invert both the dts and the driver to behave correctly.
Now I get it. Thanks! I will update the dts and driver for the gpio.