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dt-bindings: drm/bridge/synopsys: dw-hdmi: Add "unwedge" for ddc bus

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In certain situations it was seen that we could wedge up the DDC bus
on the HDMI adapter on rk3288.  The only way to unwedge was to mux one
of the pins over to GPIO output-driven-low temporarily and then
quickly mux back.  Full details can be found in the patch
("drm/bridge/synopsys: dw-hdmi: Add "unwedge" for ddc bus").

Since unwedge requires remuxing the pins, we first need to add to the
bindings so that we can specify what state the pins should be in for
unwedging.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190502225336.206885-1-dianders@chromium.org
This commit is contained in:
Douglas Anderson 2019-05-02 15:53:32 -07:00 committed by Sean Paul
parent 7f1d39efa6
commit c603625001
1 changed files with 7 additions and 0 deletions
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7
Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
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@ -38,6 +38,13 @@ Optional properties
- phys: from general PHY binding: the phandle for the PHY device.
- phy-names: Should be "hdmi" if phys references an external phy.
Optional pinctrl entry:
- If you have both a "unwedge" and "default" pinctrl entry, dw_hdmi
will switch to the unwedge pinctrl state for 10ms if it ever gets an
i2c timeout. It's intended that this unwedge pinctrl entry will
cause the SDA line to be driven low to work around a hardware
errata.
Example:
hdmi: hdmi@ff980000 {