linux-kernel - Re: [PATCH RFT 7/7] arm64: dts: qcom-mode-switch: allow 4 lanes for DisplayPort and enable QMP PHY mode-switch

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Date: Thu, 29 Feb 2024 21:00:14 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Neil Armstrong <neil.armstrong@...aro.org>
Cc: Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Vinod Koul <vkoul@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
	Conor Dooley <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFT 7/7] arm64: dts: qcom-mode-switch: allow 4 lanes for
 DisplayPort and enable QMP PHY mode-switch

On Thu, Feb 29, 2024 at 02:07:07PM +0100, Neil Armstrong wrote:
> Allow up to 4 lanes for the DisplayPort link from the PHYs to the Controllers
> and allow mode-switch events to the QMP Combo PHYs.
> 

Please adjust $subject and commit message to suite the x13s.dts...


With this series I'm reaching 4k@60 on my X13s (with some difficulty due
to current hotplug issues in the DP driver) - but 4-lane DP works, and
so does 2-lane combo.

I tested switching between DP-only and a USB device, this worked fine a
few (3-4) times, after which the USB device stopped showing up. The DP
display continued to work nicely and the debug prints from the driver
indicates that we're moving back and forth between the modes...

The problems I had when trying to implement this previously, with the
device crashing on disconnect have not been seen, across 20+
attempts.

Regards,
Bjorn

> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
> ---
>  arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> index a0fdef55a40a..6c73e0fc001f 100644
> --- a/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> +++ b/arch/arm64/boot/dts/qcom/sc8280xp-lenovo-thinkpad-x13s.dts
> @@ -556,7 +556,7 @@ &mdss0_dp0 {
>  };
>  
>  &mdss0_dp0_out {
> -	data-lanes = <0 1>;
> +	data-lanes = <0 1 2 3>;
>  	remote-endpoint = <&usb_0_qmpphy_dp_in>;
>  };
>  
> @@ -565,7 +565,7 @@ &mdss0_dp1 {
>  };
>  
>  &mdss0_dp1_out {
> -	data-lanes = <0 1>;
> +	data-lanes = <0 1 2 3>;
>  	remote-endpoint = <&usb_1_qmpphy_dp_in>;
>  };
>  
> @@ -1112,6 +1112,7 @@ &usb_0_qmpphy {
>  	vdda-phy-supply = <&vreg_l9d>;
>  	vdda-pll-supply = <&vreg_l4d>;
>  
> +	mode-switch;
>  	orientation-switch;
>  
>  	status = "okay";
> @@ -1149,6 +1150,7 @@ &usb_1_qmpphy {
>  	vdda-phy-supply = <&vreg_l4b>;
>  	vdda-pll-supply = <&vreg_l3b>;
>  
> +	mode-switch;
>  	orientation-switch;
>  
>  	status = "okay";
> 
> -- 
> 2.34.1
>