linux-kernel - Re: [EXT] Re: [PATCH v3 2/2] drm/panel: Add support for Raydium RM67191 panel driver

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Message-ID: <1561444522.9328.90.camel@nxp.com>
Date:   Tue, 25 Jun 2019 06:35:22 +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 v3 2/2] drm/panel: Add support for Raydium
 RM67191 panel driver

On Lu, 2019-06-24 at 13:12 -0300, Fabio Estevam wrote:
> Caution: EXT Email
> 
> Hi Robert,
> 
> On Mon, Jun 24, 2019 at 4:44 AM Robert Chiras <robert.chiras@....com>
> wrote:
> 
> > 
> > > 
> > > You did not handle the "power" regulator.
> > There is no need for a power regulator.
> I am sure the panel requires power to be applied so that it can work
> :-)
Yes, of course there are power lines to the panel. I will add them to
the next revision.
> 
> > 
> > > 
> > > Can't you simply remove them?
> > The reset gpio pin is shared between the DSI display controller and
> Looking at the imx8mq-evk schematics it is not clear for me what pin
> in shared between the OLED display and touch screen.
> 
> Could you please clarify which pin you are referring to?
It's about the DSI_EN pin on the DSI LCD IF physical port J1501. This
goes into RST_B_1V8 on the panel port which is used for both display
and touch resets.
> 
> > 
> > touch controller, both found on the same panel. Since, the touch
> > driver
> > also acceses this gpio pin, in some cases the display can be put to
> > sleep, but the touch is still active. This is why, during suspend I
> > release the gpio resource, and I have to take it back in resume.
> > Without this release/acquire mechanism during suspend/resume,
> > stress-
> > tests showed some failures: the resume freezes completly.
> Looking at the imx8mq-evk dts from the vendor tree I see that the
> touchscreen is not supported in mainline yet.
> 
> Maybe there is a better way to solve this, so what if you don't
> introduce the suspend/resume hooks for now and then we revisit this
> after the touchscreen driver is added?
You are right. We can do this too. I will remove it for now.