linux-kernel - Re: [RFC PATCH 1/6] dt-bindings: display: imx: Add EPDC

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Message-ID: <20220217123112.3ba70000@aktux>
Date:   Thu, 17 Feb 2022 12:31:12 +0100
From:   Andreas Kemnade <andreas@...nade.info>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
Cc:     p.zabel@...gutronix.de, airlied@...ux.ie, daniel@...ll.ch,
        robh+dt@...nel.org, shawnguo@...nel.org, s.hauer@...gutronix.de,
        kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, alistair@...stair23.me,
        samuel@...lland.org, josua.mayer@....eu,
        letux-kernel@...nphoenux.org
Subject: Re: [RFC PATCH 1/6] dt-bindings: display: imx: Add EPDC

On Thu, 17 Feb 2022 10:21:15 +0100
Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com> wrote:

> On 06/02/2022 09:00, Andreas Kemnade wrote:
> > Add a binding for the Electrophoretic Display Controller found at least
> > in the i.MX6.
> > The timing subnode is directly here to avoid having display parameters
> > spread all over the plate.
> > 
> > Supplies are organized the same way as in the fbdev driver in the
> > NXP/Freescale kernel forks. The regulators used for that purpose,
> > like the TPS65185, the SY7636A and MAX17135 have typically a single bit to
> > start a bunch of regulators of higher or negative voltage with a
> > well-defined timing. VCOM can be handled separately, but can also be
> > incorporated into that single bit.
> > 
> > Signed-off-by: Andreas Kemnade <andreas@...nade.info>
> > ---
> >  .../bindings/display/imx/fsl,mxc-epdc.yaml    | 159 ++++++++++++++++++
> >  1 file changed, 159 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/display/imx/fsl,mxc-epdc.yaml
> > 
[..]

> > +
> > +  DISPLAY-supply:
> > +    description:
> > +      A couple of +/- voltages automatically powered on in a defintive order  
> 
> Typo, definitive?
> 
yes, of course.

> > +
> > +  VCOM-supply:
> > +    description: compensation voltage
> > +
> > +  V3P3-supply:  
> 
> All of supplies names - lowercase.
> 
> > +    description: V3P3 supply
> > +
> > +  epd-thermal-zone:
> > +    description:
> > +      Zone to get temperature of the EPD from, practically ambient temperature.  
> 
> Is it a phandle?
> 
a string used in
       of_property_read_string(priv->drm.dev->of_node,
                                "epd-thermal-zone", &thermal);
        if (thermal) {
                priv->thermal = thermal_zone_get_zone_by_name(thermal);
                if (IS_ERR(priv->thermal))
                        return dev_err_probe(priv->drm.dev, PTR_ERR(priv->thermal),
                                             "unable to get thermal");
        }

[...]
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/imx6sl-clock.h>
> > +    #include <dt-bindings/interrupt-controller/arm-gic.h>
> > +
> > +    epdc: epdc@...4000 {  
> 
> Generic node name, e.g. display-controller
> 
hmm, does IHMO not make too much sense here. E.g. in the imx6sll.dtsi
we have lcd-controller next to it. So having epd-controller? But that
is exactly what epdc stands for.

Regards,
Andreas