On Thu, May 02, 2019 at 03:53:32PM -0700, Douglas Anderson wrote:
> 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.
Pushed to drm-misc-next along with patch 2. I'll let Heiko land the dts patches.
Thanks!
Sean
>
> Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> ---
>
> .../bindings/display/rockchip/dw_hdmi-rockchip.txt | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt b/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> index 39143424a474..8346bac81f1c 100644
> --- a/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> +++ b/Documentation/devicetree/bindings/display/rockchip/dw_hdmi-rockchip.txt
> @@ -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 {
> --
> 2.21.0.1020.gf2820cf01a-goog
>
--
Sean Paul, Software Engineer, Google / Chromium OS
