On Thu, Mar 27, 2025 at 04:56:53PM +0000, Christopher Obbard wrote:
> The eDP panel has an HPD GPIO. Describe it in the device tree
> for the generic T14s model, as the HPD GPIO property is used in
> both the OLED and LCD models which inherit this device tree.
AFAICT, this patch is not correct as the hotplug detect signal is
connected directly to the display controller on (these) Qualcomm SoCs
and is already handled by its driver.
Describing it as you do here leads to less accurate delays, see commits:
2327b13d6c47 ("drm/panel-edp: Take advantage of wait_hpd_asserted() in
struct drm_dp_aux").
3b5765df375c ("drm/panel: atna33xc20: Take advantage of
wait_hpd_asserted() in struct drm_dp_aux")
Perhaps you lose some other functionality too.
> Reviewed-by: Bryan O'Donoghue <bryan.odonog...@linaro.org>
> Signed-off-by: Christopher Obbard <christopher.obb...@linaro.org>
> ---
> arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi
> b/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi
> index
> 962fb050c55c4fd33f480a21a8c47a484d0c82b8..46c73f5c039ed982b553636cf8c4237a20ba7687
> 100644
> --- a/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi
> +++ b/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi
> @@ -980,8 +980,12 @@ &mdss_dp3 {
> aux-bus {
> panel: panel {
> compatible = "edp-panel";
> + hpd-gpios = <&tlmm 119 GPIO_ACTIVE_HIGH>;
> power-supply = <&vreg_edp_3p3>;
>
> + pinctrl-0 = <&edp_hpd_n_default>;
> + pinctrl-names = "default";
> +
> port {
> edp_panel_in: endpoint {
> remote-endpoint = <&mdss_dp3_out>;
> @@ -1286,6 +1290,13 @@ hall_int_n_default: hall-int-n-state {
> bias-disable;
> };
>
> + edp_hpd_n_default: edp-hpd-n-state {
> + pins = "gpio119";
> + function = "gpio";
> + drive-strength = <2>;
> + bias-pull-up;
> + };
I checked the firmware configuration for this pin on my T14s, which
does not match what you have here. Instead the function is set to
"edp0_hot" which forwards the signal to the display controller which
already handles the signal on panel power on. (And there is also no
internal pull up enabled).
We may want to describe this pin configuration somewhere, but that's a
separate issue.
Johan
