linux-kernel - Re: [PATCH 2/4] dt-bindings: Document the Raspberry Pi Touchscreen nodes.

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Date:   Tue, 16 May 2017 10:20:26 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org,
        Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Archit Taneja <architt@...eaurora.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/4] dt-bindings: Document the Raspberry Pi Touchscreen nodes.

Hi Eric,

On Monday 15 May 2017 17:03:29 Eric Anholt wrote:
> Laurent Pinchart <laurent.pinchart@...asonboard.com> writes:
> > On Thursday 11 May 2017 16:56:23 Eric Anholt wrote:
> >> The Raspberry Pi 7" Touchscreen is a DPI touchscreen panel with
> >> DSI->DPI bridge and touchscreen controller integrated, that connects
> >> to the Raspberry Pi through its 15-pin "DSI" connector (some lines are
> >> DSI, some lines are I2C).
> >> 
> >> This device is represented in the DT as three nodes (DSI device, I2C
> >> device, panel).  Input will be left to a separate binding later, as it
> >> will be a basic I2C client device.
> >> 
> >> Signed-off-by: Eric Anholt <eric@...olt.net>
> >> ---
> >> 
> >>  .../raspberrypi,7inch-touchscreen-bridge.txt       | 68 +++++++++++++++
> >>  .../panel/raspberrypi,7inch-touchscreen-panel.txt  |  7 +++
> >>  2 files changed, 75 insertions(+)
> >>  create mode 100644
> >> 
> >> Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touchs
> >> cr
> >> een-bridge.txt create mode 100644
> >> Documentation/devicetree/bindings/display/panel/raspberrypi,7inch-touchsc
> >> re
> >> en-panel.txt
> >> 
> >> diff --git
> >> a/Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touc
> >> hs
> >> creen-bridge.txt
> >> b/Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touc
> >> hs
> >> creen-bridge.txt new file mode 100644
> >> index 000000000000..a5669beaf68f
> >> --- /dev/null
> >> +++
> >> b/Documentation/devicetree/bindings/display/bridge/raspberrypi,7inch-touc
> >> hs
> >> creen-bridge.txt @@ -0,0 +1,68 @@
> >> +Official 7" (800x480) Raspberry Pi touchscreen panel's bridge.
> >> +
> >> +This DSI panel contains:
> >> +
> >> +- TC358762 DSI->DPI bridge
> >> +- Atmel microcontroller on I2C for power sequencing the DSI bridge and
> >> +  controlling backlight
> >> +- Touchscreen controller on I2C for touch input
> >> +
> >> +and this covers the TC358762 bridge and Atmel microcontroller, while
> >> +../panel/raspberrypi,7inch-touchscreen-panel.txt covers the panel.
> > 
> > The TC358762 is a standalone bridge that doesn't depend on the ATTiny
> > microcontroller used by the RPI. As it's usable standalone, I believe this
> > binding should be split in two.
> 
> Do you have a plan for how I would implement a driver on top of that
> binding change, though?  Note that we don't program the Toshiba
> directly, we only send commands to the Atmel.

I'm not too familiar with the hardware architecture, let me have a look. Is 
the schematics publicly available somewhere ?

-- 
Regards,

Laurent Pinchart