On Mon, Oct 22, 2018 at 01:46:34PM -0700, Douglas Anderson wrote: > Some eDP panels that are designed to be always connected to a board > use their HPD signal to signal that they've finished powering on and > they're ready to be talked to. > > However, for various reasons it's possible that the HPD signal from > the panel isn't actually hooked up. In the case where the HPD isn't > hooked up you can look at the timing diagram on the panel datasheet > and insert a delay for the maximum amount of time that the HPD might > take to come up. > > Let's add a property in the device tree for this concept. > > Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx> Reviewed-by: Sean Paul <sean@xxxxxxxxxx> > --- > > .../devicetree/bindings/display/panel/simple-panel.txt | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/Documentation/devicetree/bindings/display/panel/simple-panel.txt b/Documentation/devicetree/bindings/display/panel/simple-panel.txt > index 45a457ad38f0..b2b872c710f2 100644 > --- a/Documentation/devicetree/bindings/display/panel/simple-panel.txt > +++ b/Documentation/devicetree/bindings/display/panel/simple-panel.txt > @@ -11,6 +11,9 @@ Optional properties: > - ddc-i2c-bus: phandle of an I2C controller used for DDC EDID probing > - enable-gpios: GPIO pin to enable or disable the panel > - backlight: phandle of the backlight device attached to the panel > +- no-hpd: This panel is supposed to communicate that it's ready via HPD > + (hot plug detect) signal, but the signal isn't hooked up so we should > + hardcode the max delay from the panel spec when powering up the panel. > > Example: > > -- > 2.19.1.568.g152ad8e336-goog > -- Sean Paul, Software Engineer, Google / Chromium OS
