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

Krzysztof Kozlowski
2022-02-17T11:43:42Z

On 17/02/2022 12:31, Andreas Kemnade wrote:
> On Thu, 17 Feb 2022 10:21:15 +0100
> Krzysztof Kozlowski <krzysztof.kozlowski@canonical.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@kemnade.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");
> }

OK, then:
$ref: /schemas/types.yaml#/definitions/string

>
> [...]
>>> +examples:
>>> + - |
>>> + #include <dt-bindings/clock/imx6sl-clock.h>
>>> + #include <dt-bindings/interrupt-controller/arm-gic.h>
>>> +
>>> + epdc: epdc@20f4000 {
>>
>> 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.

Still we have "lcd-controller", not "lcdc". Since this is only for epd,
then "epd-controller" seems reasonable. The same as we use
"interrupt-controller" (not "ic"), "dma-controller" (not "dmac" or "dc")
and so on. See also list of recommended generic names from DT specification.

Best regards,
Krzysztof