Re: [PATCH v2 1/6] dt-bindings: drm/panel: simple: Add no-hpd property

Sean Paul
2018-10-29T16:16:51Z

On Thu, Oct 25, 2018 at 03:21:29PM -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@chromium.org>

Thanks for the series, Doug, I've applied it all to drm-misc-next-fixes for
4.20.

Sean

> Reviewed-by: Sean Paul <sean@poorly.run>
> Reviewed-by: Rob Herring <robh@kernel.org>
> ---
>
> Changes in v2: None
>
> .../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