Re: [PATCH v3 3/6] dt-bindings: add binding for Sitronix ST7586 display panels

Noralf Trønnes
2017-08-04T18:04:51Z

Den 04.08.2017 18.51, skrev David Lechner:
> On 08/04/2017 04:48 AM, Noralf Trønnes wrote:
>>
>> Den 04.08.2017 00.33, skrev David Lechner:
>>> This adds a new binding for Sitronix ST7586 display panels.
>>>
>>> Using lego as the vendor prefix in the compatible string because the
>>> display
>>> panel I am working with is an integral part of the LEGO MINDSTORMS EV3.
>>
>> Is this display available outside of this Lego part?
> No, it is not.
>
>> If not you can remove the properties you don't need for this particular
>> display setup. Another st7586 display with a different panel would need
>> a different initialization sequence and compatible string, so we can
>> add properties when/if that happens.
>
> OK. so I will drop power-supply and backlight.
>

And the dc/reset gpios should be required properties since your display
won't work without them (or rather they're hardwired that way).

> Should I remove these from the driver as well? There are some panels
> out there that could use them.[1]
>
> [1]:
> http://www.buydisplay.com/download/manual/ERC240160-1_Series_Datasheet.pdf
>

Yes, because that display won't work with the driver as-is, so it's
really dead code. If someone wants to add support for that display,
they'll add the necessary code. When maintaining code for 10-20 years,
it's important to not add code that 'might' be used in the future.
Let the future take care of itself and keep the codebase slim :-)

Noralf.

>>
>> Noralf.
>>
>>> Signed-off-by: David Lechner <david@lechnology.com>
>>> ---
>>> .../bindings/display/sitronix,st7586.txt | 26
>>> ++++++++++++++++++++++
>>> 1 file changed, 26 insertions(+)
>>> create mode 100644
>>> Documentation/devicetree/bindings/display/sitronix,st7586.txt
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/display/sitronix,st7586.txt
>>> b/Documentation/devicetree/bindings/display/sitronix,st7586.txt
>>> new file mode 100644
>>> index 0000000..dfb0b7b
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/display/sitronix,st7586.txt
>>> @@ -0,0 +1,26 @@
>>> +Sitronix ST7586 display panel
>>> +
>>> +Required properties:
>>> +- compatible: "lego,ev3-lcd".
>>> +
>>> +The node for this driver must be a child node of a SPI controller,
>>> hence
>>> +all mandatory properties described in ../spi/spi-bus.txt must be
>>> specified.
>>> +
>>> +Optional properties:
>>> +- dc-gpios: D/C pin. The presence/absence of this GPIO determines
>>> + the panel interface operation mode (IF[3:1] pins):
>>> + - present: IF=011 4-wire 8-bit data serial interface
>>> + - absent: IF=010 3-wire 9-bit data serial interface
>>> +- reset-gpios: Reset pin
>>> +- power-supply: A regulator node for the supply voltage.
>>> +- backlight: phandle of the backlight device attached to the panel
>>> +- rotation: panel rotation in degrees counter clockwise
>>> (0,90,180,270)
>>> +
>>> +Example:
>>> + display@0{
>>> + compatible = "lego,ev3-lcd";
>>> + reg = <0>;
>>> + spi-max-frequency = <10000000>;
>>> + dc-gpios = <&gpio 43 GPIO_ACTIVE_HIGH>;
>>> + reset-gpios = <&gpio 80 GPIO_ACTIVE_HIGH>;
>>> + };
>>
>