From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Paul Subject: Re: [PATCH 1/5] dt-bindings: drm/bridge/synopsys: dw-hdmi: Add "unwedge" for ddc bus Date: Wed, 5 Jun 2019 16:21:01 -0400 Message-ID: <20190605202101.GG17077@art_vandelay> References: <20190502225336.206885-1-dianders@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20190502225336.206885-1-dianders@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Douglas Anderson Cc: Heiko Stuebner , Sandy Huang , Andrzej Hajda , Laurent Pinchart , Rob Herring , linux-rockchip@lists.infradead.org, Neil Armstrong , Mark Rutland , mka@chromium.org, Sean Paul , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, David Airlie , linux-arm-kernel@lists.infradead.org, Daniel Vetter List-Id: devicetree@vger.kernel.org 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 > --- > > .../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