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| Started by | Rob Herring <robh@kernel.org> |
|---|---|
| First post | 2017-03-20 16:30 +0100 |
| Last post | 2017-03-21 09:10 +0100 |
| Articles | 5 — 3 participants |
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Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 Rob Herring <robh@kernel.org> - 2017-03-20 16:30 +0100
Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-20 16:40 +0100
Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-20 17:20 +0100
Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 Rob Herring <robh@kernel.org> - 2017-03-20 18:10 +0100
Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-21 09:10 +0100
| From | Rob Herring <robh@kernel.org> |
|---|---|
| Date | 2017-03-20 16:30 +0100 |
| Subject | Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 |
| Message-ID | <tn7pT-6E2-3@gated-at.bofh.it> |
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>
> ---
> Memory-mapped configurations can be supported by amending the binding to
> make mandatory either the {data,enable,rs}-gpios properties, or a "reg"
> (and optional "reg-names") property.
>
> As the driver doesn't support this yet, and there are different ways to
> organize the register map (some wirings use different addresses for
> reading and writing, to simplify bus glue logic), this is left for a
> future improvement.
>
> v2:
> - Added rationale below "---".
> ---
> .../devicetree/bindings/auxdisplay/hit,hd44780.txt | 44 ++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt
>
> diff --git a/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt b/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt
> new file mode 100644
> index 0000000000000000..ee4054da458d412f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/auxdisplay/hit,hd44780.txt
> @@ -0,0 +1,44 @@
> +DT bindings for the Hitachi HD44780 Character LCD Controller
> +
> +The Hitachi HD44780 Character LCD Controller is commonly used on character LCDs
> +that can display one or more lines of text. It exposes an M6800 bus interface,
> +which can be used in either 4-bit or 8-bit mode.
> +
> +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
> +
> +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?
> + - internal-buffer-width: Internal buffer width (default is 40 for displays
> + with 1 or 2 lines, and display-width for displays with more than 2 lines).
> +
> +Example:
> +
> + auxdisplay {
> + compatible = "hit,hd44780";
> +
> + data-gpios = <&hc595 0 GPIO_ACTIVE_HIGH>,
> + <&hc595 1 GPIO_ACTIVE_HIGH>,
> + <&hc595 2 GPIO_ACTIVE_HIGH>,
> + <&hc595 3 GPIO_ACTIVE_HIGH>;
> + enable-gpios = <&hc595 4 GPIO_ACTIVE_HIGH>;
> + rs-gpios = <&hc595 5 GPIO_ACTIVE_HIGH>;
> +
> + display-height = <2>;
> + display-width = <16>;
> + };
> --
> 2.7.4
>
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| From | Geert Uytterhoeven <geert@linux-m68k.org> |
|---|---|
| Date | 2017-03-20 16:40 +0100 |
| Subject | Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 |
| Message-ID | <tn7zA-6Hw-23@gated-at.bofh.it> |
| In reply to | #1604686 |
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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| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Date | 2017-03-20 17:20 +0100 |
| Message-ID | <tn8ci-7du-19@gated-at.bofh.it> |
| In reply to | #1604696 |
On Mon, Mar 20, 2017 at 04:27:01PM +0100, Geert Uytterhoeven wrote:
> 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?
Please do.
thanks,
greg k-h
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| From | Rob Herring <robh@kernel.org> |
|---|---|
| Date | 2017-03-20 18:10 +0100 |
| Subject | Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 |
| Message-ID | <tn8YG-7Pz-37@gated-at.bofh.it> |
| In reply to | #1604696 |
On Mon, Mar 20, 2017 at 10:27 AM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> 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>.
Yes, I know. I want to be able to read the binding and validate the
dts file, so I need to know what is the correct flag.
Rob
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| From | Geert Uytterhoeven <geert@linux-m68k.org> |
|---|---|
| Date | 2017-03-21 09:10 +0100 |
| Subject | Re: [PATCH v2 4/5] dt-bindings: auxdisplay: Add bindings for Hitachi HD44780 |
| Message-ID | <tnn1E-xY-21@gated-at.bofh.it> |
| In reply to | #1604813 |
Hi Rob,
On Mon, Mar 20, 2017 at 6:00 PM, Rob Herring <robh@kernel.org> wrote:
> On Mon, Mar 20, 2017 at 10:27 AM, Geert Uytterhoeven
> <geert@linux-m68k.org> wrote:
>> 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>.
>
> Yes, I know. I want to be able to read the binding and validate the
> dts file, so I need to know what is the correct flag.
For the LCD Controller's bus, the GPIOs are wired straight, so they should
be ACTIVE_HIGH (unless there's an inverting buffer in between :-).
The backlight is separate from the LCD Controller, hence the polarity
depends on the actual hardware configuration.
Is it worth documenting that?
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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