From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: David Lechner <david@lechnology.com>
Cc: dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
Mark Rutland <mark.rutland@arm.com>,
Kevin Hilman <khilman@kernel.org>, Sekhar Nori <nsekhar@ti.com>,
linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 3/6] dt-bindings: add binding for Sitronix ST7586 display panels
Date: Fri, 04 Aug 2017 22:39:37 +0300 [thread overview]
Message-ID: <2830608.h203mxr23Z@avalon> (raw)
In-Reply-To: <cc04e31c-2206-2f0c-0f92-7ef096bfd9da@lechnology.com>
Hi David,
On Friday 04 Aug 2017 10:51:37 David Lechner wrote:
> On 08/04/2017 09:54 AM, Laurent Pinchart wrote:
> > On Thursday 03 Aug 2017 17:33:47 David Lechner wrote:
> >> 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.
> >>
> >> 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
> >
> > How does this work ? Do you have a single GPIO on your system connected to
> > IF[1], with IF[3:2] hardwired to 01 ?
>
> LEGO has not made the internals of the display publicly available, so I
> cannot say for sure. But I assume that IF[3:1] is hardwired to 011. This
> causes pin D1 to assigned to the signal A0, which is what we are calling
> the dc gpio here.
>
> If IF[3:1] were hardwired to 010, then pin D1 would be not not used and
> there would be no A0 signal.
>
> So, basically, we can infer the state of IF[3:1] by the fact that we
> have a dc pin or not.
OK, now I understand what you mean. Maybe you should phrase it a bit
differently to make it clearer ? How about
dc-gpios: Specified or the GPIO connected to the panel's D/C pin (also called
A0). The property is required when the panel operates in 4-wire mode (IF[3:1]
= 011) and prohibited when the panel operates in 3-wire mode (IF[3:1] = 010).
By the way, if the signal is named A0, why don't you call the property a0-
gpios ?
> >> +- 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)
> >
> > Please use the OF graph DT bindings (a.k.a. ports) to describe the
> > connection between the panel and its source.
>
> I am afraid that I do not understand this request. What would the source
> of the panel be? There is nothing like a SoC LCD controller that is
> driving this panel.
My bad, I should have read the panel datasheet before replying :-S Please
ignore this comment.
> >> +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>;
> >> + };
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2017-08-04 19:39 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-03 22:33 [PATCH v3 0/6] Support for LEGO MINDSTORMS EV3 LCD display David Lechner
2017-08-03 22:33 ` [PATCH v3 1/6] drm/tinydrm: remove call to mipi_dbi_init() from mipi_dbi_spi_init() David Lechner
2017-08-04 13:16 ` Noralf Trønnes
2017-08-03 22:33 ` [PATCH v3 2/6] drm/tinydrm: generalize tinydrm_xrgb8888_to_gray8() David Lechner
2017-08-04 7:27 ` Noralf Trønnes
2017-08-04 13:20 ` Noralf Trønnes
2017-08-03 22:33 ` [PATCH v3 3/6] dt-bindings: add binding for Sitronix ST7586 display panels David Lechner
2017-08-04 9:48 ` Noralf Trønnes
2017-08-04 16:51 ` David Lechner
2017-08-04 18:04 ` Noralf Trønnes
2017-08-04 14:54 ` Laurent Pinchart
2017-08-04 15:51 ` David Lechner
2017-08-04 19:39 ` Laurent Pinchart [this message]
2017-08-05 16:13 ` David Lechner
2017-08-04 17:36 ` Noralf Trønnes
2017-08-03 22:33 ` [PATCH v3 4/6] drm/tinydrm: add support for LEGO MINDSTORMS EV3 LCD David Lechner
2017-08-05 18:19 ` Noralf Trønnes
2017-08-05 19:54 ` Noralf Trønnes
2017-08-07 16:03 ` David Lechner
2017-08-03 22:33 ` [PATCH v3 5/6] ARM: dts: da850-lego-ev3: Add node for LCD display David Lechner
2017-08-03 22:33 ` [PATCH v3 6/6] ARM: davinci_all_defconfig: enable tinydrm and ST7586 David Lechner
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