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SubjectRe: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780
Hi Rob, Greg,

On Mon, Mar 20, 2017 at 4:15 PM, Rob Herring <robh@kernel.org> wrote:
> On Fri, Mar 10, 2017 at 03:15:20PM +0100, Geert Uytterhoeven wrote:
>> Add DT bindings for an Hitachi HD44780 Character LCD Controller where
>> its M6800 bus interface is connected to GPIOs.
>>
>> Memory-mapped configurations are not yet supported.
>>
>> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt

>> +Required properties:
>> + - compatible: Must contain "hit,hd44780",
>> + - data-gpios: Must contain an array of either 4 or 8 GPIO specifiers,
>> + referring to the GPIO pins connected to the data signal lines DB0-DB7
>> + (8-bit mode) or DB4-DB7 (4-bit mode) of the LCD Controller's bus interface,
>> + - enable-gpios: Must contain a GPIO specifier, referring to the GPIO pin
>> + connected to the "E" (Enable) signal line of the LCD Controller's bus
>> + interface,
>> + - rs-gpios: Must contain a GPIO specifier, referring to the GPIO pin
>> + connected to the "RS" (Register Select) signal line of the LCD Controller's
>> + bus interface,
>> + - display-height: Height of the display, in character cells,
>> + - display-width: Width of the display, in character cells.
>
> display-{width,height}-chars

Makes sense.

Greg: As this is already in char-misc-next, shall I send an update for
the bindings
and the driver?

>> +Optional properties:
>> + - rw-gpios: Must contain a GPIO specifier, referring to the GPIO pin
>> + connected to the "RW" (Read/Write) signal line of the LCD Controller's bus
>> + interface,
>> + - backlight-gpios: Must contain a GPIO specifier, referring to the GPIO pin
>> + used for enabling the LCD's backlight,
>
> Active state?

That's typically handled via the last cell of the GPIO specifier, cfr.
GPIO_ACTIVE_HIGH / GPIO_ACTIVE_LOW in <dt-bindings/gpio/gpio.h>.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

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